So if I put on a nazi blog that said something akin to um I’m going to kill all of you… Given I don’t know who they are beside username and where they are at would I be arrested? How is that different from what the 20 year old did? He was just more specific as far as I can tell.
I suspect that the mere utterance is enough for it to be a threat, even if a rational person would know it was not serious.