It's actually pretty easy to explain, once we take into account the leftist / liberal mentality about violence.
They consider words to be violence and physical violence not to be violence. Easy, right? No first amendment as far as these klowns are concerned.
So it's perfectly acceptable to them to respond to word violence with physical violence. And if the words come from someone who isn't in lockstep with their groupthink? Well, just ask Maxine Waters what needs to happen.
And that's just their twisted view as far as violence goes. The same general lack of mental horsepower is used when they try to think about almost any subject.