Sin, I agree with some of what you're saying here to a point (I'll explain further below), and you and I agree on other issues as well.
But not this one.  Violence of any kind is NEVER the answer unless your life or well-being is in immediate jeopardy.  I could never condone anyone, whether it's a white supremacist running people down in a car, or a radical Leftist shooting police officers in Dallas, being violent towards one-another as a first form of communication.
If you have a legitimate claim of self-defense, that's one thing.  But there was NOTHING self-defense about running people down with a car.  From what I've heard, he wasn't boxed in, and he had other avenues of escape.
To explain further what I said above, in principle, I agree that the Left, as of late, has been pushing a lot of people's buttons.  They're behavior, both on social media and in public, has been pretty abhorrent.
But there is no excuse for this kind of behavior, just as there is no excuse for punching a Nazi in the face whom is exercising his First Amendment Rights.  These people were exercising their Right to Protest, and that should always be respected, whether or not anyone agrees or disagrees with their message.
In that context, I'm afraid I must respectfully disagree with you here in the strongest terms.  This kind of violence was completely uncalled for and cowardly.