Isn't the corollary to this rule that you learn to be an jerk by being an jerk?
He's always be intense. Better that he not learn it's okay to be an jerk athlete, too.
But at this point, I don't see why you send him down. Just sit him down for a few games, or drop him in the order.
oh grow up.
You learn to play the game by playing the game, let him play the game and quit worrying about how many batting helmets or bats he buys or how big of a fine he's racked up in the club house.