1. It's not condescending at all. And note that I'm not a NYC resident any more, so I'm not exactly elevating myself here. What I know about NYC is getting pretty stale. I think I will always understand the city, but I won't understand the particulars.
2. I'm not making local residency a litmus test. I'm saying that there are places where residency is more or less important. Where I live now is not particularly special. It's not as nice as Durham/Chapel Hill or what I imagine Charlotte to be (haven't been there in a long, long time) but it's not that different. I don't think I'm particularly more knowledgeable about the political environment here than people who study American politics.
NYC is different. It's just not like the rest of America and if you haven't been there, it's hard to appreciate. For one thing, the "white" people in NY aren't like white people elsewhere in America. That's largely because a fairly high % of the white people are Europeans and have spent little time in America outside of NY. Even a lot of native "white" people who are residents aren't typical of other places. For instance, my barber in Park Slope was Uzbeki. He looked white and identified as white. But he lived in a Uzbeki neighborhood (yes, there's an Uzbeki neighborhood -- there are hundreds of different ethnic enclaves and fissures arise when they collide) and that surely remained an important shaper of his views. He likely had little experience of American racial politics.
One of the more reliable predictors of political leanings is the personality trait 'openness to experience." NYC -- at least parts of it -- is openness to experience realized on Earth. 7th Avenue in Brooklyn is the commercial strip for NYC. When I was there, there was precisely one "American" restaurant: a diner. Within walking distance, there was a Peruvian restaurant, two Thai places, an Indian place, an Asian future, a legit authentic Mexican place, a couple of Italian places where the staff had Italian accidents, and I'm sure a couple that I'm forgetting. Oh, the corner delis were all Korean.
To walk on 7th Avenue is to have a completely different experience than pretty much anywhere in America. As mentioned before, it is racially diverse almost to a comical degree, and everything is international. That's not to say that there aren't racial tensions (there are, especially over education) but it's a different world.