Every reason you think you have for doing something is an illusion. The meaning of words are illusions, there's nothing that a word that someone told you actually means. So if you take offence at someone for doing something, it's made up inside your head, so there is no reason ever to punch someone, unless you want to.
Katt Williams seem to be going off the rails. A brief look at his recent history dispells any idea that he has a clear and valid reason for throwing a sucker punch at a person on stage. Although no one was arrested I believe that this should clearly be a police matter.
There is really no excuse for Katt Williams to randomly sucker punch someone at the Beanie Sigel concert. From all accounts, the punch came out of nowhere. Even if there was provocation, nothing justifies the escalation to violence. There's just no scenario in which anyone could say that a sucker punch is justified.
No, I do not think Katt Williams had a good reason to sucker punch someone at the Beanie Sigel concert because Katt Williams is a very erratic person and has been known to act irrationally in the past before. Williams has been the subject of a lot of controversies regarding violence these last couple of months and was probably reacting to a situation that didn't have to be resolved with violence.