From a few minutes of privacy-mode Googling, NAMBLA seems to have lost its tax exempt status in 1996. (Layperson take upcoming:) If Donald Trump gave them money, he couldn't write it off on his taxes. Therefore, a reveal of his taxes wouldn't show any connection to NAMBLA.
This to me just seems like Trump is moving into Bill Simmons' Tyson Zone: we're at the point where literally any story about Trump, no matter how illogical or insane on its face, is presumed true "because TRUMP".