People in Western society have been indoctrinated into believing that political violence is never the answer. That shit is drilled into your head from the moment you enter school to the moment you leave, and by the time that happens, most people have internalized it completely. It even goes so far that people distort history. For instance they might argue that South Africa was liberated by Nelson Mandela, who was a saint that did not condone violence against collaborators or government forces. Or MLK - because he was reasonable and didn't prefer violence, he was obviously opposed to all instances of it, and would have been outraged by how these kids are acting.
I'm guessing its the most prominent example of cognitive dissonance in our society, which has always relied upon tremendous violence to further it's goals.