Interstate rest area stops

Visited an uncle in New York State a few years ago and his neighbor was a Police Officer who came by to say hi. He asked me where I stayed at night when I was on the road, and I told him I pulled into Rest Areas for a few hours of sleep. He told me it was illegal to camp in New York Rest Areas and I told him I didn't have any beer in the camper and camping without beer was just sleeping outside. The next evening he stopped by with a couple of cold beers.