The comments here are pretty clearly protected by the 1st amendment. It's not a "true threat" by the standards of US jurisprudence. https://en.wikipedia.org/wiki/True_threat
However, just because it's narrowly legal to say something doesn't mean it's a good idea; this kind of thing does tremendous self harm to the speaker's public reputation.
However, just because it's narrowly legal to say something doesn't mean it's a good idea; this kind of thing does tremendous self harm to the speaker's public reputation.