[nitpick]The T does not serve customers, it serves passengers[/nitpick]
While I cannot honestly and in good conscience condone the amount of force used by the T employee, I fully support her efforts to defend herself against the assailant's assault. That's right, Mr. Wilkerson was clearly the assailant in this case, and he is guilty of assault and public intoxication. Receiving poor directions is no justification for shoving a camera in anyone's face. Right there you are guilty of assault and any form of self defense within the confines of the law (as in you obviously can't fire a rocket launcher at the guy) is fair game. I can't say that I'd put out that opinion as an employer however. I also certainly wouldn't fire the employee on the spot either. There is certainly a due process being skipped here, a full and thorough investigation should be conducted prior to any personnel action taken.
If I were the employee I'd press charges on the intoxicated assaulter, then go after my job back (although if I were the employee, I'm not sure I would have used the same amount of force).