why would their death be bad?

Because you don’t have a crystal ball. You seem to think you can magically know for sure that premeditated murder of Fuentes would prevent suffering (“I support it if it does”.) Forget legality, morally you shouldn’t get to decide that someone dies because you “know” their death will prevent suffering. Like I said, what if other people made life-and-death decisions about killing other civilians based on that metric. Imagine if the “enemy within” extremist right start making decisions that way - they probably think you and people you love will harm their nation. Determining harm and exacting punishment should not be a matter of personal surety. Especially when it’s a podcaster, which again, is the origin of your argument as per your “silencing the voices” assertion which you argue could reasonably save “tens of millions”.

let’s assume Stalin’s regime wasn’t fascist. What changes?

You using him as an example of Western fascism.

Pick one.

That’s a moral decision, not a legal one. Like you are so fond of saying, policies can be determined by either. I don’t think a person should be denied trial because of morality, not because it’s in a book. Should explain why I don’t support fascism as well. We’re not going to agree. You think murder is right, I don’t. I’d support a war to unseat Hitler and the SS, but at that point it’s not murder, it’s combat. There would be moral boundaries in such an event. I wouldn’t support individuals marching into a German newspaper and opening fire on civilians and hoping that did the job.