Advice -- Booting a player
Ad the DM/ST/GM, you always have the authority to remove a player from the group when you feel that their participation is a detriment to the fun of the game. Your enjoyment is included in that. You're working hard to craft the kind of story or experience that you want to run. If he's not playing ball with that, you're under no obligation to give him a spot, no matter what you've said previously.
If he's taken this dispute public, that's a huge sign of immaturity, and I wouldn't want that in my game anyway. If you feel like you've given him a chance to explain himself to the extent that you believe is fair and he hasn't decided to work within your rules, then yes, remove him from the game, then calmly explain what happened to the other players. You asked him to make changes, but he refused. You were unable to reconcile, and after he decided to make this public, you had no choice but to remove him.
Being open and honest is the only appropriate way to respond to things like this.