Poor mental health and deliberate antisocial behavior that you could call malicious often go hand in hand. It's not very clear to me over the internet here whether he's having a laugh behind an act, making some calculated move for self-gain, really perceives what he's done as good and true, or even whether he sees it as socially good somehow despite being an act. It could be malicious behavior, it could be unhinged, it might be both, but I doubt it's neither.

I don't think believing a conversation AI to be sentient is a mental health issue. More an effect of lacking insight. In context of people praying to some tree spirit it almost seems rational again.