I clicked on a few more, a decent number of the links aren't really advocating for murder/violence at all.
There was one link I clicked on that did lead to someone advocating for murder (Kokesh), I didn't recognize who it was and their name wasn't highlighted as an instance Admin.
Looking at the modlog for that user, they have had a number of comments removed for advocating for murder/violence, so this is probably just a comment that slipped through the cracks.




Legal Eagle has a good list going with sources over here:
https://www.youtube.com/watch?v=hybL-GJov7M
It's a 40 minute long video, so not something you can just send to someone with that attitude and say, "Watch it!" and expect them to actually watch it. But it would be a great way to get a list started with some sources. Judging by a list of timestamps in the comments, there are ~100 individual items from this video.