Well as stated the idea isn't all that new. Think about it...put together what you personally think would be the best politician you could imagine. I'm talking your personal political Golden Child. Now tell me there wouldn't be lots and lots of haters of that person's stances. Of course there would be...it's literally unavoidable.it probably should be at this rate. they draw hate because they don't do anything to improve our nation, or solve our problems.
1-5 years in prison, some community service, and the like, seems like it would be more than enough to dissuade this without being ridiculous. and that would still be harsher than the punishment for spitting on a member of the general public.
if its actual assault, i would get it. but this is essentially "they were mean to me in public".
I think it's key that the statute in question (18 U.S. Code § 111) may "allow" for a 20y sentence that in no way means that's really on the table regarding this particular incident. I think it MUCH more likely it goes down along the lines you posited.