He dresses as female because he was castrated. As soon as we learn he's "actually" a boy, in Eli's POV, all the pronouns are male. So Eli isn't a trans woman. Eli is a boy. But somehow being castrated means he can't be a boy anymore so he goes around as a girl even though he doesn't identify as one.

Was the clerk recommending this male? Because if so that explains a lot about why they'd consider this a horror book. Honestly, I've been baffled by the crossover between disgust and horror because the whole torture porn model conflates the two in a way I don't get.

Anyway, I definitely sympathize with your hate review because I admire you had the energy to get through the book!