It's possible such a threat is credible, but I doubt Chris's threats would qualify. Usually. He was somewhat menacing to Mary Lee Walsh, and that was in the real world. He was touchy-feely with Megan, and posting crudely drawn porn of her saying he did it so he wouldn't rape her was. . .sketchy as hell. He obviously actually did commit vehicular assault on Michael Snyder.
I think anyone who has spent enough time on the Internet deliberately annoying people has got the occasional death threat here and there but I can't imagine actually calling the cops over it without it being seriously credible. IMO if I'm the target of it and couldn't give less of a shit, why should the cops?
Probably, because cops usually take threats involving guns seriously. Whether he'd be ultimately prosecuted or convicted would be highly fact-dependent. The fact that nobody appeared actually intimidated by his bullshit in the least would be contextual. It isn't, strictly speaking, necessary that you actually successfully intimidated or frightened the person. Just the fact you try and fail to scare someone because they're particularly brave doesn't make you not guilty.
However, the fact that an entire community of people messed with him continually in spite of his "threats" really inclines me to think they aren't "true threats" at all in the legal sense, or at least the more famous ones aren't. A funny one would be when he threatened that black guy in The GAMe PLACe and then instantly backed down.