They don't seem to mind when it's their side doing the violence. I also happen to think this is staged. Just like the alleged racial epithets and spitting. Zero evidence this is from opponents.
Prove it. On the other hand, I can prove routine violence on behalf of the Left over the last 50 years. And plenty of it.
This is no more than an attempt to discredit and demonize the TEA Party movement. It's what the Left does.