Unfortunately we don't have enough information. If a guy with a gun threatens your life, it's reasonable to act in self defense, but we don't know whether or not that happened. But the outcome of this individual case is independent of the bigger picture: You're confident without that information. You also felt that it was somehow relevant to point out that somebody in a crowd was a pedophile. I hope you try to understand that, for many people, your attitude is the scary one that threatens their society, and the lives of their loved ones and their friends. I too wish people wouldn't riot, but to simply ignore the monstrous crimes against civilization that are spurring them, or the poisonous hatred coming from the groups that are cheering this child's killings, is a message that you're not interested in a good faith attempt to save society - that all that matters is who the political enemy is.
And, yes, in a sense you're right: Framing civil unrest and riots as just villains destroying our precious country with no consideration for why it is happening is exactly how you get to a place where lots of people die.