He's not even leaving "because AI". He's literally leaving to focus more on AI stuff.

> I plan to study how AI agents debug code and whether debugging tools that can make them more effective at that.

> I want to use AI agents to bring some of my hobby project ideas to life.

> I’m keen to reap the benefits of AI

and addresses the anti-AI view:

> AI detractors think that AI won’t really work. I think it will. (ed. for brev)

The main reason then is the concern of the velocity of the rollout and the increased pervasiveness of AI. Too fast, too much.