It’s transphobic because cis people aren’t oppressed for being cis. It’s like saying white people should have safe spaces for support for “struggles unique to white people”. There are no struggles unique to white people. The whole world is literally our safe space. It’s the same for cis people. You bring up being born with a uterus that doesn’t work. Then is that group going to include trans men with non-functioning uteri? There are also cis women born completely without uteri as opposed to having one that doesn’t function. Shouldn’t that group include trans women? I don’t deny that there are differences between cis people and trans people. That’s obvious. But so too are there differences between one cis woman and the next. Cis women as a whole do not have the same narrative. Trans women experience many of the same things as cis women, and suffer many of the same societal ills. Excluding us from female spaces because we aren’t cis, because our bodies are different, is only adding to the oppression we already face. If someone wants to have a group, a safe space, for people to talk and share the struggle of not being able to bear children or having had a miscarriage, more power to them. But don’t exclude people just because they aren’t cis.