Write the book. Seriously. Disabled and unwell children need books that speak to their specific experiences, as well as to the more general experience of being a child in a reality-denying, body-hating culture. If there's a gap in the market for that book, write it. When it's done and published, tell me, and Il'll get it stocked in the shop I work in. Or if there is a book out there that already does the above wonderfully, again, tell me the name and I'll stock it.
There is room for this book too! Our kids are growing up in a body-hating, reality-denying culture, that has become more and more narrow in what it allows certain kinds of bodies to be and do.
It's a real stretch to say that this book, which again, you haven't read! is telling children with physical disability they can't utilise medical care to improve their physical functioning.
I am done with discussing this book with you now. I think I've been more than fair. I hope you will consider moving any further conversation you want on disability representation in children's literature more generally elsewhere.