I can understand Eren's friends trying to stop him and all. But I won't complain if he actually succeeds killing at least the Marleyans and neighboring nations. His act of violence is justified, even though it is for the worse of the world. Either way, I just feel that this "alliance" and the chapter, in general, was rushed. It is good seeing the old crew back, but this feels really cheesy when you put it in the context of the story itself. The average Eldia is in the right about thinking of revenge for what the world made to them for the last 100+ years, but I'm not turning a blind eye for what the Eldians did to the world when they had all the titans under their control.
But I still would love Eren killing everyone. And if he got killed by some mumbo jumbo after it, I wouldn't be mad at all.