Living in the NYC area all my life, I would tend to agree with the man who posted this comment. Although, I would not take it so seriously.
NYC is very big, fast paced, very convenient, extremely competitive and could be difficult to live in if you are not used to the vibe of the city. Because of these traits, at times it could make someone leery and untrustworthy of others. Its more of a defense mechanism than it is rudeness.
Also, dating in NYC is very difficult. It goes back to my theory of "how many items there are on a menu equals the likelihood of engaging in meaningful dating experience" scenario. Simply, the more available men, the more hooking up and less solid dating/relationships. The less available men the more likely you will make the best of what you have and dating could be more substantial. Clearly, this is painting with a broad brush but it does seem to be true most of the time. No one move to NYC to find a husband, get a dog and a house with a white picket fence. And if they do, they learn fast that NYC is not made from that cloth.