The same reason you hear little from the feminists. Muslims are a politically protected so-called underclass. Yet, female genital mutilation happens every day in Africa, Indonesia, and even England. Ever hear a word from the National Organization of whiny Women (NOW) about the atrocities that occur every day around the world?
OR...maybe the GLBT bunch is just too damn cowardly to give the Muslims crap. They know USA politicians and white-guilt liberals are softer targets.