Unfortunately, one of his accounts was already gone by the time I got to it. These three were still up though. I tried to archive as many threads he posted as well, for posterity. As usual, no one had bothered to do much of it before, even though this has been out for at least a day.
Where archive.org archive are missing, it's because it will not allow archives (you first have to confirm that you are 18 and up). But the most prolific account he had did allow archives.
Narrow_Frosting_1539:
archive.today: page 1 - page 2 - page 3 - submissions
AmericanNick7:
archive.org: page 1 - page 2 - page 3 - submissions
archive.today: page 1 - page 2 - page 3 - submissions
AmericanNick:
archive.today: comments - submissions 1 - submissions 2
And here's a thread where he posted now-deleted comments in which he made his intentions clear. Apparently, TwoX moderators did not report it to the authorities, and while another user cautioned against it, he did call it "tempting" and said "you're welcome to try".
Some quite interesting stuff here.
EDIT:
Here's the posting history of the guy who said that killing Kav is "tempting" and "you're welcome to try".
archive.today: comments - submissions
archive.org: comments - submissions
I look at it the way the Mexican Mafia hires coyotes. If the person knows fully that they will be killing the dog, child, parent, then cry if anyone tries to take away said being away from them, then they are perfect. Sure, that's a serial killer, but it's a serial killer willing to do the job.
Same idea, the vast majority of lefties are fairly stupid and benign. But, if you want to start a riot, you just find the people willing to do it, and the deal is made. If you want a lone assassin, you make it seem like such and such is evil until someone is willing to do the job.
Sure it's evil, but it is very effective.