Hmmm. I get the impression of a control freak, my way or the highway, personality in this description. Throwing fits during conversations is not a sign of maturity, and I’m actually now thinking he is trying to take control of your campaign with his actions. You let him change characters once already, which caused you to retool some aspects of the campaign and now you’ll need to do it again.
Frankly, he does not sound like someone happy being a player, since your description is of him makes it sound like he was only GM-ing in prior play sessions. Give him one more chance if you want, but be prepared to let him walk away.