I agree with the sentiment that there's plenty of fault to go around here. The one item that made me snicker was the taunting comment. Seriously? Taunting players occurs all game long. Proximity makes a difference?
It’s my opinion that once a fan enters the playing surface, they are trespassing. And the players should be allowed to do whatever they want to those fans. Claim self defense in the courts if you have to.
If we had security treat them like they do streakers, then I think this problem goes away pretty quickly.