*disclaimer - I have not seen this, but only heard about it on the news.
IMO it's never right for a player to physically, or even verbally, attack a fan. I suppose he just had enough of some kind of abuse, but the league cannot, and should not, condone this sort of action.
But the fan should have more class than to trash talk a player like that. If all he was doing was clapping because his team got an advantage, then that's not bad sportsmanship. But if he was making fun of the guy, then he ought to not be surprised when the dog bites back!
I really need to see this video. It sort of reminds me of the time that Shanahan (I think) squirted the fan between the glass with the water bottle. The guy has his mouth pressed right between the two glass panels saying crap to Shanny, and Shanny just turns around and soaks him through the crack. EVERYONE was laughing their asses off, the announcers, Shanny, and even the guy doing the trash talking. I don't know if he ever got in trouble for it.
But this other thing reminds me a bit too much like the NBS fiasco in Detroit a few years ago. The player just needs to let security deal with it.