I recently had a job and one of my tasks was to investigate NAMBLA. I did over 100 hours of research on NAMBLA and inspected their internal documents and private communications.
If you go here you can see that GLAAD (a "mainstream" "gay rights" organization - Gay & Lesbian Alliance Against Defamation) from 1994 through 2001 included a link to NAMBLA's website on its page of gay organizations.
The gay lobby (a group that touts sexual autonomy and freedom and promotes youth experimenting with sex, etc.) knows that there is no logical reason for them to critique a youth's decision to have sex with an abult male, when they do in fact advocate that youth have right to express them selves sexually. The gay lobby even presses hard to lower the age of consent laws. for boys. Why? Because they want boys to be able to have sex adults without it being a crime - there is no other reaosn for them to push for a lower age of consent law.
http://216.239.33.100/search?q=cache:kiBu4lvXM5EC:www.glaad.org/org/topics/%3Ftopic%3D211+nambla+spirit+of+stonewall+&hl=en&ie=UTF-8