You can be arrested for eating a ham sandwich on Sunday while dressed in a tuxedo, so long as the Officer is willing to state that he believes there must be a law against such activity. That doesn't mean you violated any law, or ordinance, or that you'll be convicted.
This webpage may be helpful: Rights, NY
Technically, he was operating a vehicle (and I believe, said vehicle must be operated on the public roads, not sidewalks just like any other vehicle), and according to the law he must show his license to operate said vehicle if such license is issued. (yeah, sounds screwy to me, too.)