As loathsome as these pro-Palestinian types are, I don't like the idea of suing these groups for publicly advocating for Hamas. You should be able to say what you want and not get sued as long as you don't slander someone.
They go far beyond simply "advocating" for Hamas. What you call advocating, when you throw in trespass, damage to property, resisting arrest all in concert, would you agree they're providing material support to Hamas? If so, that's a rather serious federal crime, which the feds care little about. A civil suit is nothing compared to that. Would you have described similar actions in support of Isis or al Qaida as free speach?
I'd note the US has survived to this day with two, more if you count fringe parties, Communist Parties and the Nazi Party have survived, I suspect in part due to the lack of organized violence.