If you find this horrifying (and I hope you do, because there can be no moral justification for celebrating murder), then I encourage you to really think about whether we would not be better off without such extremist language poisoning people's minds. We have to try to stop escalating, or the cycle is going to destroy our society.
My conclusion is that you don't mind making apocalyptic statements about actions you think are dangerous to society, which sits uncomfortably with your asking other people not to.
It would bring on the end of a society. It might well happen in the US case, they've been heading in a pretty dangerous direction rhetorically. If we take the Soviet Union as a benchmark they probably have a long way to go but that sort of journey seems unnecessary and stupid.
"You shouldn't do anything unjustified" is an uncontroversial and useless prescription.