If the police are threatening to arrest non-compliant customers for TRESPASSING, then I’m now thinking that the restaurant staff called the police. I don’t think the police can charge someone with trespassing unless the property owner files the complaint.
The restaurant industry in NYC has been fighting this mandate because of the financial losses the restaurants have incurred; many restaurant owners have also made it clear that they have no intention of checking papers at the front door.
But if a restaurant can be fined for serving unjabbed diners, then they're left with two options, both of them bad: 1) simply close the doors of the restaurant (and in some cases, lose a family business), or 2) have someone else do the heavy lifting for them.
Outside of a handful of liberal bastions, that experience in the restaurant would have been unpleasant enough that anybody with any remnant of a conscience would make sure they never darkened its doors again. But if the owner is looking at a substantial fine for non-compliance with the mandate, he or she may have believed that the best bad solution available was to call the police.
The real outrage wasn't the cops coming into the place and saying, "Ihre Papiere, bitte."; it was that everyone else in that restaurant didn't immediately get up and leave.
As far as I'm concerned it already is. Right now I wouldn't patronize a NYC business establishment at gunpoint -- even if it was run by an openly defiant owner who refused to enforce the stupid restrictions. I'll travel to Kabul before I go to NYC.