If thats their perogitive so be it. If they feel that strongly about it Im not gonna say they should be stopped. I personally frown upon it, but every action has a reaction....and that reaction will have just as violent reaction or the law gets invovled one of the two. The person usually gets whats coming to them.
Your free to say what you want just as someone is free to knock the shit out of you for saying it if they are prepared to face the consequences. Yea its a called assault, but thats the glory of free will. And you start taking that away there is a major problem.