Kathy is not a favorite, but she's 5'4'' and 120 lbs. At 56 she's no threat to a secret service agent. Madonna couldn't figure out which end of fuse to light, she's not bombing anything. They're entertainers. Like Trump is, you don't take everything they say seriously.
BOTH should be openly and actively investigated, just like any other crackpot who would do such a thing. If I wrote an email to the president threatening his death, I would have FBI greeting me when I got home after work.
Doesn't matter WHO the President IS -- these actions promote TREASONABLE offenses.