Only a small minority of that NYC Jewish population grounds itself for the Sabbath.
Sabbath observant Jews were among Adams’ earliest and strongest supporters. He may be doing this for a couple of big donors only.
You’re only thinking of Manhattan. In Brooklyn and Queens there are entire neighborhoods that observe the Sabbath, where the streets are closed for children to play while their fathers attend synagogue and their mothers rest on the day of rest. Bronx on Pelham Parkway, too, and I think Riverdale (no relation to Archie), and some parts of Staten Island.