It just seems incredibly odd for there to be so many lines in a book about gender insisting that there is no way to refer to someone (in the English language, at least) without implying gender. She even mentions the possibility of using „it“ at one point!
I’m liking the book otherwise, but every time the narrators ponder about pronouns without even considering „they“ I have to ask myself if there is any point in ignoring it or if she genuinely just forgot. I don’t think it’s possible for her to have not known about it considering how well-read she was and how long it’s been in use.
Hmm, true but it was used in the case where the specific person being referred to was unknown. “Somebody left their umbrella.” It was not used the way OP is talking about, for a gender neutral individual.
It was also used for someone known, but whose gender was not known or being hidden. Shakespeare used they this way. From there, it’s not a great leap to use they to refer to someone without a gender.