I finally have a few minutes to give my take on this and the reports on this.
1. The overt Trump character was the one actually doing the raping. That would be Mr. Garrison. The one being raped, the President of Canada, also could be a Trump character but wasn't as overt as the role Mr. Garrison was playing.
2. If you look at it this way, the Trump who is the campaigner is raping the Trump who was the President. (a comment on his self-destructive nature possibly?)
3. The real conversation in this episode, combined with the last episode, is not a specific candidate, but the war of P.C. You have two extremes where people embrace radical political correctness, where one can't even say Bruce Kardashian is a hero and attacking every single so-called micro-aggression, to then taking the rebellion against this too far and jumping on whatever crazy populist is the opposite of that, even if it is cheering the calling for the actual rape and murder of someone.
So the 'you know, I learned something today' moment was really a tale of people jumping back and forth on every extreme bandwagon just because it wasn't the other bandwagon, and setting aside what they really believe.
Trump, like Bruce Kardashian, were just symbols, and ironically, drove off in the sunset together.