Turner has been a savage, rabid, foamflecked nazist loon all of his professional life and most of his adult life. He certainly didn't need any help from the FBI to go over the edge, he's been treading thin air for at least a decade.
What if he had said, "These judges should be charged with high treason and, if convicted, sentenced to death?" Is that better or worse.
IMHO, wishing someone will die or saying you wish the other person's death is free speech.