But yes, obviously serious threats of violence are not protected speech.
The fact that your statement is becoming more and more true in the United States is an indictment.
Because then you don't really have any rights. They can't formally punish you for speech but they can punish you for breaking the same unrelated law a million other people broke without knowing and that only you were prosecuted for, "coincidentally" right after you said something they didn't like.
They can also contravene a number of other legal safeguards along the way, and disregard judges' orders.
https://en.wikipedia.org/wiki/Detention_of_R%C3%BCmeysa_%C3%...
https://en.wikipedia.org/wiki/Deportation_of_Rasha_Alawieh
https://en.wikipedia.org/wiki/Detention_of_Mahmoud_Khalil
https://en.wikipedia.org/wiki/Detention_of_Mohsen_Mahdawi
https://en.wikipedia.org/wiki/Activist_deportations_in_the_s...
It appears the US has elected an administration that wants to turn the country into a lawless shithole, where the powerful do whatever the fuck they want, and they deliberately fuck with laws and safeguards, and deliberately target their political enemies (e.g. student activists), to flex how powerful they are.
I kind of hate the thing where people want to make this the part that matters, because Trump is a massive outlier who doesn't care about that and says the thing he's not supposed to say.
But the people who still do the prosecution under the pretext and then don't admit to why are even worse, because they're doing the same thing and then lying about it on top of that. If all you do is punish people for not lying, that's not going to solve anything. You need to take away their ability to trump up charges against random people.
Dispute that this should constitute a crime as much as you want (and please, do. Take it to court, get the laws changed, go into politics, get the US fixed, this is bullshit) but for as long as it is: being charged with a crime for "doing crime and teaching others to do the same crime" is not a first amendment violation.
The current regime (before it was a regime) got away with a lot of very bad speech because "the first amendment says all speech is allowed, no matter what" and should be made to hold everyone to the same standard they hold themselves to.