Pretty sure you know this person more than I would
Didn't say anything about universal sisterhood. but if he was once biologically a she, she could have gotten pregenat. This is not a dis on women who were genetically male once, but it is a reality all women share. Doesn't make it more or less "real", just a shared reality.
Ah, I didn't realize you were talking about the body. Thought you meant something more subjective about socialization.
Nah, purely body. I assume that biological girls who understand and/or present themselves as boys, probably have a deep fear of rape, since it seems to be a "common" punishment that our oh so healthy society does when it finds that someone who is self-presenting as a boy, has a vagina.
I'm not one to quibble, but "biological girl" isn't the preferred term for most trans men, at least for most of the ones I've read of and those I know personally.