Should fans be able to mouth off to players?

Not that I am a huge sports fan, I stumbled on this story about a pro player getting fined.

A woman yelled some snotty stuff at him, he responded with some profanity.  If it wasn't profanity, should he have still been fined for responding?  Paying for a ticket to game doesn't give a fan the right to be abusive.  In football and baseball, there are many more fans at the games and they aren't usually up close, like at some basketball games. Of course at work, if someone mouths off to me, and I make any comment, they run and whine to the first person who will listen.

Here is the story from msn.com