In any case, I do not find any support for the idea that you can't discuss the property with the person you send to your landlord. It wouldn't really be possible to say "this is a great place to live" and respond to "why?" with "can't tell ya!".
Now if you tried to sue because your landlord reneged on your monetary reward, then you might not win because you weren't licensed or something, but that's not at all the same as it being illegal for them to pay you.
NY may have a reputation for corruption, but things aren't that bad.
The legalities of referral fees come into play if you are a real estate agent, and you pay a fee to another agent who failed to renew their license, I believe.