I think maybe she thought the disability stuff was all bloodless metaphor for embodiment in general - she was writing a lot of stuff about embodiment at the time - and that nobody would ever read the MC's description and think "Oh, someone who is just like me/this friend of mine!"

Possibly she also thought that a society in which PWDs were feared and abused and traumatized and ostracized was total SFF and wouldn't ever happen until eugenics made disabilities super-rare? That one is wrong in so many ways.