I’m not sure we did watch the same series tbh from what you’re saying.
To use your same logic, isn’t crushing people by the walls falling down in the rumbling just as hypocritical? Eren is killing his own people in order to save them.
I’d like to see why you think Attack on Titan was all about the survival of Paradis above everything else because I do not see how that was ever the point after Marley and the outside world was introduced. If it was about survival and nationalism for Paradis and killing everyone else then why is most of that arc showing that the people outside the walls aren’t devils, if the whole point was just to say “fuck you you should die because Paradis is more important than billions of people in the whole world”?
If you rewatch the series, you’ll see plenty of moments hinting at the upcoming moral dilemma of the rumbling, such as the royal family’s choice in season 3, Erwin giving up on his dream for the future of humanity and choosing between Armin and Erwin.
Attack on Titan spent several episodes and even arcs showing the horrors of war, so it has always presented war as bad, but I think what you mean is that it suddenly became about genocide being bad, but when was genocide ever considered good in AoT? I would understand that criticism if the whole beginning of the series was about Armin and co. committing genocide and saying it’s cool, but that’s not the case. Jean’s entire character in the later chapters is about how he cannot sit back and reap the rewards he knows come from bloodshed on a global scale, Armin committed a genocide on the harbour with his Titan and that changes his view and changes him to a character experiencing guilt from that as well as survivor’s guilt from knowing Erwin should have been chosen instead of him, and he wants to make a choice that is right without being an emotional decision caused by attachment to the people of Paradis.
Yes it’s rushed, but there’s nothing contradictory about any of the characters’ choices and the direction of the story late on.