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.
It is historically proven as the first step to violence. People seem to think that words don't matter.
They matter very much. Just because you can read millions of words a day, doesn't mean they're not powerful.
Support him or no, he didn't deserve to die for his political beliefs.
I definitely believe that people should be more understanding of each other, and less quick to jump to insults and othering, but we know so little about this situation, to be so confident that it was caused by speech seems extreme.
I am also aware that a lot of the political violence of the last few years ended up not being motivated by the reasons one might naturally expect.
At the root I agree in principal though. It's, for example, still possible he picked a bad fight with an unstable individual in a bar last night (over something not politically related) and they followed him to the event he was speaking at to shoot him. I'm not as convinced I've seen that kind of thing happen "a lot", but it's true we don't have post validation yet.