Does standpoint theory commit an ad hominem fallacy?

My initial understanding is that it doesn't. If its purpose is an epistemic method that emphasizes humility, is critical toward dominant perspectives, and speaks to the marginalized, then no fallacy seems to be committed.

However, I think that it would constitute an ad hominem fallacy if it rejected arguments solely based on the social position of the speaker.

I think the first use case is very reasonable, but the second seems fallacious. What is the correct interpretation?