It depends on the phrasing he used but if what he said is a true threat, then that is legally actionable.
Bellyaching about a group is protected. Making a threat you have the means to carry out is not.
“Making a threat you have the means to carry out is not.”
They reported that he said something like “somebody ought to” rather than “I am going to.” Since the media lie constantly, though, I’m not going out on a limb for them.
In America, the principle has always been “everything is allowed except what is specifically prohibited,” rather than “everything is prohibited except what is specifically allowed.”
Hate speech laws make it difficult to know what is prohibited. Some nasty leftwad moron can pop up and characterize almost anything you say as “hate speech.”