I'd argue that for most people, attraction isn't based on genitals but the rest of the package.
So if she likes girls, a boy who's mostly indistinguishable from a girl would probably still tick the box. No guarantee, but it's not that weird.
Same as the bajillion basically-straight-guy+otokonoko series out there.
Or Ookami Shounen wa Kyou mo Uso wo Kasaneru, where one of the female leads with similar hang-ups to the girl in this one still seems only attracted to the lead guy when he's cross-dressed even after the reveal, with at least some implication that she's gay with an exception.