The Supreme Court almost always judges in favor in free speech, including justices like Sotomayor. A place this frequently comes up is in rap where rappers frequently tend to rap about specific people and propose or fantasize about violent acts and even murder being committed against them. Eminem and his ex-wife Kim is a more or less well known example. And the Supreme Court has ruled, repeatedly, that it's 100% legal. A relevant court case is Elonis vs US [1]. He said some extremely explicit and provocative things, and the court ruled 8-1 in favor of throwing out his conviction. Interestingly enough, the sole dissenting vote was Clarence Thomas!
It is legal in the US as long as you are not intending and likely to incite imminent lawless action. Eg. To give a recent example, it's completely legal to chant "from the river to the sea, Palestine will be free" despite some interpreting that chant to be calling for genocide.
[1] - https://en.wikipedia.org/wiki/Elonis_v._United_States