You are correct on this point. I think that if you look at the rhetoric on this issue, however, you will notice something interesting: there is an awful lot of this kind of comparison to other minority movements that have become mainstream in order to legitimate the issue, especially the comparison to racism. But this kind of appeal is just an emotional one to make people feel bad, because they feel bad about racism. There is very little to actually substantiate the parallel to discrimination based on race, or based on religion for that matter. That is my assertion, anyway, to which I invite you to tell me what the parallel is, other than the one you’ve mentioned - starting off as a minority movement (I would think there are more charlatan minority movements than ‘righteous’ ones.)
BTW, you claimed you are open-minded, and you do in fact appear to be the most open-minded SSM proponent I have come across on these forums.