I was one of the ones who wrote the prez, and I'm glad to see he took a proper step. The next one, in my view, is dismissal from the union for this punk (and probably the loss of his job). And I have no sympathy for the idiot. If I wore my firm's T-shirt and pulled such an outrageous stunt, I'd be fired for sure.
I also hope the police consider pressing assault charges.
I don't see how they can dismiss the guy from his job. Maybe slap his wrist internally, but the guy would have too many avenues of appeal to fight a dismissal. And it would be bad for employee morale.