This is an odd comment. Of all the things to focus on in a movie, you choose this?

Nixon pioneered a lot of the modern culture war tactics. So it's in character that someone doing an anti-authoritarian stunt in the late-60s would do it against Nixon and his power structure.

I mean, if we choose the metric of "presidents capable of not resigning in disgrace", then Nixon is literally the worst, and by an infinite margin.

Though I doubt the writers disagreed, that closing bit was describing the choices/values of the characters. It completed the story that began in the movies first few minutes, and in that it was perfection regardless of whatever value judgement you'd place on those decisions yourself.

Yeah, truly a misstep, going after a criminal president from 2 decades earlier. Weird hill to die on, dude.