It was just an unkind jab at the fact that the examples given of exposure to different people and cultures were helping someone cross the road and giving up a seat on the subway. That jibed with my experience living in NYC - it's not particularly conducive to expanding your horizons; the diversity is there if you really want to go out and meet people, but mostly it will be courteous distance on the street and most of your deep interactions will be within your filter bubble, same as anywhere.
Unlike my current town, NYC has mosques, but I didn't actually learn anything about Islam or Muslims living there, compared to when I actually lived in the Middle East and made friends for life there. I ate at Chinese restaurants and shopped in Chinatown but wouldn't say I gained any cultural insights. But living in Singapore for a year and making friends with Singaporeans, Indonesians, and Chinese people - there I learned a lot.