"Have placard-bearing drivers begun their own reclaiming of reclaimed public space?"

That is the question posed by Streetsblogger ddartley, who last week snapped these photos of a city government vehicle parked in the new Madison Square pedestrian plaza. He got just close enough to spot the placard behind the windshield when:

This guy wearing some sort of NYPD uniform showed up and got in and
drove off. Okay, it’s not like he was committing murder or anything,
but every time a cop breaks a law for all to see, it’s just a little
more poison in the world. This suggests that even after these fancy new
pedestrian-only plazas have been built, they are under threat from
being parked on by placard-bearing NYC employees who remain, at least
as far as parking, 100% completely above the law. Well, for now!

It’s surprising, really, that it’s taken this long for such behavior to come to light. What can, or what should, DOT do to nip it in the bud?