The story is not clear. If he got access to the event thanks to tickets provided by a client, then he most certainly did do something out of line. Suppose a client provides tickets to a sporting event to my company and I use them. Then I end up getting thrown out for being drunk and obnoxious, with everyone seeing what happened, well, you better believe that the client is going to be mad and demanding that I be fired.
Slam dunk for his case in my opinion!