It is not possible for violence to occur via the internet. And if you believe that posts on the site somehow constitutes harassment to an illegal degree, contact law enforcement.
Now that KF is back up (good job, CF), please find me one post on KF that involves the planning of violence which wasn't either deleted or ridiculed into oblivion by the other posters there. If it's so common, this should be an easy task, right?
It's not just a message or speech. It involves IRL stocking, harassment, and violence against people they target based on hate and discrimination.