This is the most important point. Agreed your idea would make a surprising plot twist. I’d give it two points for originality. But I think it would be out of character too much if Sherlock came up on top with such a plot of murder. The tea scene and the roof-top scene are such superb scripting. I don’t think the writers would ruin it by any additions. The writers also said the solution would be simple. Your solution is not simple. It’d need a lot of explaining. I fear you expect something complicated when in fact everything is as obvious as it seems.
The idea that the whole episode is one big plot of Sherlock and Mycroft is ridiculous and disappointing. The emotional drive lies in the fact that Moriarty looms big in the background and Sherlock is helplessly waiting for him to strike. Adding the layer of your plot would seriously diminish that drive and ruin everything that is special about the episode. Don’t you see that your solution would deplete the episode of all dramatic and emotional impact and meaning?
For example Mycroft’s greatest fear come true. That one day he had to place his duty over his little brother. At first he didn’t even realize this was the day. Thinking he was serving his country and causing only minor to no damage to Sherlock when he’s telling Moriarty a few details from his brother’s life. (After all what can he do? Tease him with his nickname from school?) He only understands later what he has done. His pain when he realized that he helped destroy his little brother whose protection was the prime purpose of his life. I don’t know about you but I like to see regret and a moving family reunion. Much more than dialogue lines like “So our plan worked, little brother, what do we do now?” (Besides I am very much convinced that Moriarty did let himself get caught so he could question Mycroft about Sherlock. It would be below him if others really could get to him.)
Or Sherlock cornered so badly that he is driven to threaten Moriarty with terrible torture to save his only friends. Only moving if it’s real. Or Moriarty killing himself out of the sheer will to triumph over Sherlock. His action would be much less shocking if he was convinced that he was dying anyway. Everything would be much less dramatic if all was part of a plan and Sherlock was just acting.
Besides a smooth running plan with him always on top would be deadly boring for Sherlock. From his earlier experiences with Jim and Irene we can see that he likes rough games that even involve pain and temporary defeat. It’s interesting for him if he learns something about himself and there are ups and downs and strong emotions. He would rather prefer to be beaten and then turn the table in the very last moment.
Of course you want to see Sherlock concerting the whole episode. Who wouldn’t want to see him clever and all? But the main problem is that the episode is about how Sherlock deals with defeat and failure and death. (Defeat: couldn’t get Moriarty convicted despite acting as prime witness. Failure: to realise that the computer code was not real, Death: well dying or not) It’s a tragedy. The hero has to die, well, or fake his death. Sherlock has to burn to ashes to rise like a phoenix in series tree.
It’s just more dramatic that Moriarty is always on top during the episode and Sherlock comes up with a plan to survive only in the very last hours. From a dramatic angle a narrow escape from an evil plotter is always more interesting than watching an evil plotter succeed. (And your idea is an evil plot no matter what you think.) So it’s necessary that he completes Moriarty’s scheme. Sherlock has to do what he tells him. His only act of opposition is that he jumps but refuses to die in the act. The one possibility that Moriarty has not taken into account when he played Sherlock like a puppet. If all was part of Sherlock’s plan it would discard his noble action and his cleverness.
Besides if Sherlock planned it all and didn’t tell John right afterwards that he’s alive, it would by far be more cruel than faking suicide when being forced and in the aftermath seizing an opportunity to vanish that presented itself.
Your tea solution would also equal character assassination for Sherlock and Moriarty.
Becoming a “good man” and acting out your plan is a contradiction. I’m surprised that your idea of a good man includes poison murderers or people that drive other people to suicide by making them believe they were poisoned. Because my definition would strictly exclude that. The fact that Moriarty kills himself is not important. It would still be murder by deception. For example by this definition:
In Maine, a person is guilty of murder if he or she intentionally or knowingly causes the death of another human being, engages in conduct that manifests a depraved indifference to the value of human life and causes death, or intentionally or knowingly causes another human being to commit suicide by the use of force, duress, or deception (Me. Stat. tit. 17-A § 201 )
Granted it’s not English law. But English law as I understand it is case law. That means murder by deception could become law at any time should a case as such present itself and a judge create a precedent. Besides it’s still morally wrong. Every life is sacrosanct even if it’s the life of a bad guy like Moriarty. You can’t measure life against life. Otherwise you open the can of worms called utilitarianism.
In my view poisoning or pretending to and driving people to suicide is evil and an extreme opposite to the very idea of a hero. It would ruin Sherlock’s image. TRF is about Sherlock becoming a hero. So your solution can’t be correct.
BTW does Sherlock look like a grand schemer waiting for his big plot to finish? No, he certainly looks depressed like he knows he’s going to die in the end. Don’t tell me he’s faking it all through the episode. That’s unlikely. On the other hand it’s according to Conan Doyle’s canon that Holmes should accept his death as a possible outcome. He bugs Watson repeatedly with speeches like how satisfied he is with his career and his only wish is that he could take Moriarty with him. Before you come up with a “Told you so!” Hold your horses. He wouldn’t attack. He’s not looking for Moriarty but running away until he’s tricked into a dead end. Holmes didn’t kill Moriarty on purpose he just defended himself and Moriarty falls. You see the writers keep the spirit of that story. But your plot would seriously violate it.
Now for Moriarty:
I think it is owing to the popularity of Andrew Scott’s Moriarty that the writers let him go all by himself, not demystified and undefeated at the highest peak of his triumph over Sherlock. It’s a brilliant plot idea. Usually Moriarty is utterly defeated at that point and kills himself in his ferocious attempt for revenge. Attacking a much younger man without a weapon on the brink of a cliff. (Conan Doyle’s version) (One can easily understand it as suicide in a mad fit. Therefor: “You’re insane!”) Other versions are: He kills himself accidentally in his attempt to escape the police that caught him. (“The Woman in Green”) Holmes throws him during a fight. (Jeremy Brett series: off a cliff, Rathbone movie “The Adventures of Sherlock Holmes”: off a roof) It seems the writers wanted to respect the dignity of the character. Your plot would spoil that beautiful scripting of the roof-top scene.
Your plot would also be history repeating. What’s the novelty in showing us that Sherlock would be prepared to die to stop Moriarty? We have already seen that in the pool scene in TGG. When Sherlock aims at the explosive he makes his point very clear in a very heroically way. I don’t see why the feat should be repeated and what’s more in such a treacherous way? In the pool scene it is quite clear that Sherlock would only resort to killing Moriarty and himself if there is no other way out. He could have shot Moriarty regardless of what happened to himself. The result would be the same. But he didn’t do it. Because aiming at the explosive was meant as a “If I am going to die then I am going to take you with me.” Not as a “I am going to kill myself to kill you.”
A few words about some minor topics you mentioned:
You understand “burn” in a very literal way.
“Burn” clearly is used in a metaphorical meaning. Like in “burn in hell”. Sherlock used that metaphor to give Moriarty an idea what terrible things he’s about to do to him. He also uses this metaphor because Moriarty constantly threatened to “burn the heart out of” him. He’s basically saying: Okay, I will burn my heart out myself by hurting you. He’s referring to the fact that he has feelings for Moriarty as an equal but his friends mean more to him. He will hurt Jim because he has no other chance. He refuses to feel sorry about it because Jim is the one who forces him. I’m not sure if it means it will make him sick to torture. He was quite resolved with the Cabbie. Sherlock can be ruthless when he wants something. But Moriarty does not know that. Nobody has seen what Sherlock did to the Cabbie. So Moriarty probably mistook Sherlock for a brainy weakling (Just like himself?) and that’s why he is so surprised about Sherlock’s resolve to do bad things to him.
You put too much weight to the blinding light during the confrontation in the roof-top scene.
I think it just a cinematographic means to break the spell. After all two guys starring at each other threateningly can easily become involuntarily funny and stereotypic. So even when Benedict Cumberbatch and Andrew Scott are extremely good actors, it’s better to add something that makes the setting different. I don’t like the solution. I find the light annoying and awkward. The actors too, I presume, because Andrew’s irises looked small like a needle pin, it must have hurt to stare into the light. But it certainly stays in memory and so it served its purpose. Another explanation would be that it’s their “moment of privacy”. The audience is blocked out because it’s something between them. We are not supposed to know what Moriarty actually saw as a means to keep the character mysterious.