What have you heard? I don't see anything that says they aren't available.
Paying $75/night at the KOA to basically store your camper.
Paying $200/night for a cheap hotel room in the city, plus parking.
That's $275 a night for a single dingy hotel room in the city.
I've paid $100/night, and would pay again, to stay in my camper, with my bed/shower/toilet/kitchen/etc in Liberty Harbor. Its an easy walk to the PATH, or a quick drive through the Holland Tunnel to downtown Manhattan and everything that NYC has to offer.
No juggling suitcases, no checking into a hotel, no worries about where to park while you're there.