When I'm on vacation, especially in Disney, it's pretty much about enjoying myself and letting go of worries and minor angers. If someone was specifically rude to me, I would likely be upset, though most of that sort of thing (like people cutting in line in front of you) is usually just a mistake on the other person's behalf that they are happy to correct should I point it out. And when they say sorry, I reply, "No worries!" And I mean it! So as far as the Poly pool, I'm not the pool police, I don't want to be the pool police, and I don't want to spend my time poolside worrying if someone is there "illegally."
I say, enjoy yourself, and don't worry about what other people are doing. And yes, that means I'd hold open the gate--probably with a smile.