It wasn’t NAMBLA, it was Lambda:
https://www.lambdalegal.org/about-us/history
Lambda Legal was founded in 1973 as the nation’s first legal organization dedicated to achieving full equality for lesbian and gay people. When founder Bill Thom filed an application in early 1972 to establish Lambda Legal Defense and Education Fund, he borrowed from the bylaws of another newly established organization—the Puerto Rican Legal Defense and Education Fund (now Latino Justice PRLDEF).
Because of the overwhelming climate of prejudice against gay people, we became our own first client: A panel of New York judges turned down our application to be a nonprofit organization because, in their view, our mission was “neither benevolent nor charitable.” With pro bono help, Thom appealed to New York’s highest court, which finally allowed Lambda Legal to exist as a nonprofit organization.
I could never keep the acronyms straight when I was in the Army either.