That doesn't prove a point. It says "we can't convince enough people that we're right by rational arguments, so let's scare the shit out of them by showing by example what a bogeyman terrorist might accomplish". If this kind of stunt were pulled by advocates of a national security state to convince people of the need to give up their civil liberties you'd be screaming bloody murder. And this stuff is not "nonviolent civil disobedience" either. "Direct action" maybe, but you're also trying to sell the "propaganda of the deed" as if it were Ghandi's.

guaranteed to evoke a violent reaction from police is to challenge their right to "define the situation." --- David Graeber citing Marc Cooper