>>281737387
It's the end of his story. Once he thought he achieved his goal he mellowed out. He never lashed out against the world like Furuta. Instead he did what he had to do, regardless of how horrifying and cruel, to regain what was stolen from him. Even at the very end he didn't regret his actions, which is why I love him so much.
Personally I'm more fond of Furuta's destructive hatred, but Batista has a fantastic character arc with the right amount of edge and tragedy to create a satisfing bitter sweet ending.
Noh Mask's eccentricity being dropped so suddenly feels weird, but you can explain it by seeing it as a persona he adopted to deal with the tower and his cruelty. I don't know what else would explain it.