Could it also have something to do with the fact that nowadays what’s called “the right” in the US are extremists and what’s called “the left” are center-right/right wing?
You’re the asshole in that situation. Don’t expect that any parking place is yours until it’s empty, especially when you have no idea when the people actually parked in the space are leaving. You should never be blocking traffic waiting to park in an occupied space because you assume they’re leaving.