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.
There is no inherent threat of violence in saying "this person is a threat to democracy". This is why the US has strong protections for speech, so that we don't get arbitrary determinations of what's acceptable and what's not.