He didn't have a proper sniper with a good scope, it was just, reportedly, an "AR-15 style rifle." In which case, good shot. Very good shot. That's a long ways, and proper sniper equipment is hard to get and harder to conceal.
Edit: I had no clue how close this actually was, at the time of writing the details hadn't been released. 150 yards... yeah even I could make that shot. How do you miss that...
That said, enough shit could certainly be problematic. Not nearly as bad as petrol, and harmless from a military point of view, but definitely an effective form of civil disobedience...