You know, maybe we should just remove this old guy from existence.
I don't know why the second Nui figured out he was controlling her friend, let alone the other children, she didn't try to coordinate to kill him, or at least subdue him.
FFS, pattern-recognition or not, he clearly is, if not evil, partly responsible for all the shit that's going on. Even if he was managing the entire tree, he HAS to be corrupted to some degree - a lot of people with good intentions have ended up corrupted and unknowingly sabotaging themselves in this series, after all.