As someone who has only had to use a chair as I got older, I don’t have a problem with his story or feel it’s inauthentic. A wheelchair to me is a tool, it’s not part of my identity. I’d love to never have to use one again. I’ve said it before here, that I don’t think being disabled makes me who I am, it’s just something I have to deal with, and has kept me from doing things I want to do. So while it may not represent your version of disability, it does mine.