I don't think it's a well-known thing, but their other properties, like the George Washington Bridge show "no photographs" signs. I make sure to take a cell-phone photo every time I ride my bike up there.
They prohibit photographs on their transit system: http://www.panynj.gov/path/pdf/PATH-Rules-Regulations-12-20-...
The consensus I get from doing some research is that they are overreaching. Anyone can make any policy they want. Anyone can approach anyone else in public and ask them to do whatever they want. Whether or not there is any force of law behind those policies or questions is up to the courts to decide.
A few years ago, someone was going to sue the MTA for their photography policy. Apparently there is a law on the books regarding suing public-benefit corporations (of which the MTA and Port Authority are); if they agree to settle with you, and you choose not to accept the settlement, you are personally liable for their legal fees if the court awards you a settlement that's less than their legal fees. So of course, these policies can't be changed, as an individual can't out-resource the government.
I don't know if it's true or not. I'm not a lawyer. I'm not a professional photographer. I'm just a guy who tries to visit the park with a few pieces of film every now and again.