See, I was feeling the same thing. I think there's parts of this issue he's leaving out. My main question is, if this guy was causing some sort of rift, and he was an 'acquaintance' why the hell was he brought back for a 2nd session, and possibly a 3rd. It didn't sound like he was going to request the player not return unless they, themselves, opted not to.
This guy sounds like a total ass of a DM, and his table sounds even worse. Why be upset about an in game situation like that? Jesus, it's just a game. If the guy is a newbie, help him through it. I would let my seasoned players live with their mistakes, never a new person at the table. And with such a stupid thing as well. He used the wish to jump at the boss? I have no idea what that even means, but as a DM or even a player, why would you say "hey, that's kind of a dumb way to use the wish, lets rethink that." He says they gave him warning before hand, but it doesn't really sound like that's truthful.