Be good to know if he is going to be AI before turns get submitted though. AI may not be all that bright, but he is a little more cunning than someone who stands still and doesn't spend his taxes.
Llama took care of it. Anyone can actually set a nation to AI, you just have to resend their turn to another email, but if someone currently in the game does it I think it has a chance of making their real nation stale because of copy protection or something. I managed to set Atlantis to AI when he left earlier without any damage but I didn't want to risk it again.