Well truthfully, there are sources that how that Marsha P. Johnson did in some instances ask to be refered to by her dead name and male pronouns. But that fact does not make her in any way less trans. The transgender experience is not simple, and because of this there is no one narrative that transgender people have to live by to be seen and respected in their identity.
I don’t want to dive into the discourse, but every piece of evidence I have seen points to Marsha being a transgender woman.
As for Sylvia Rivera, I cannot say I have ever seen evidence that she said something like that. But if anyone has evidence of it I am more than willing to looking at it, but as of now I have never seen anything to suggest that. (To be fair I haven’t looked into her that much yet). I am sorry I don’t have a better or longer answer for you.