Turns out he was there to update some cameras on the roof that pointed out to Union Square. I talked to him for a while, and while he wouldn't specifically say who owned them, he did say "they could read a business card from 300 yards away."
This was probably before there was much facial recognition going on, but it stuck with me that we were only one of many buildings with these set ups. I always heard about London being over-surveilled, I guess the NYPD did a much better job of keeping quiet about it.