Boudicca90
Muse
AFAICT the assumption among the girls' parents was that the sort of penetrative sex which might well lead to pregnancy was possible now whereas before it was physically impossible. Seems to me they could reasonably require more intensive chaperoning now that the risks have changed.
Nothing has changed just because the cisgender girls have the ability to become pregnant. Putting someone with a penis and someone with a vagina in a room together doesn't automatically ensure they will have sex, like the parents seem to think. If a chaperone would make them feel better about things, fine. But it still sends a message to the trans girl that she is not to be trusted.