If you read the actual rules of PANYNJ, there is nothing banning photography by the public on airport grounds except in "sensitive areas" such as TSA checkpoints and the FIS areas. The roof of a parking garage really can't be considered a "sensitive area". Allied Barton doesn't seem to understand this, but PAPD usually does. In my experience, AB will try to chase us off almost every time, but when I have pushed back and they call in PAPD, the result is a "have a nice day, carry on" to the spotters and a nice long chat between the cop and the guard.
What IS prohibited is
press activity on airport grounds without prior authorization from Media Relations. Commercial activity is also banned without prior permission. So by carrying a press pass (no matter if it is real or fake), you are actually running afoul of the stated policies of the airport.
I have long held that this is where the confusion stems from. Security erroneously equates all photography with being a function of the press, while PAPD will make the distinction. After all, they do always ask us why we are up there.