My son has a form of Autism. The label PDD-NOS is alphabet soup and not very descriptive of how he is as a person. I've never read a Sanderson interview. But I'm in the midst of reading Elantris right now. The child who only mutters numbers , Adien, sounds spectrum(ish). As does his sister, Kaise, as she can retain so many facts, learn a gazillion languages and has some issues with her social skills. I have not finished the book so I don't know if much more of this comes out as the story progresses. But the 2 kids show sort of the extreme examples of the spectrum. (My son falls in between these two examples.)
Renarin, from the Stormlight Archives, strikes me as having some spectrum qualities but his powers and how the magic of his world affects him has yet to be fully described. Adolin, who doesn't seem to "get" that flirting with other women while on a date is socially unacceptable and can't seem to "figure" out women sounds about like someone who is so lightly touched that he wouldn't quite qualify for a diagnostic label. Many of us who are Autism Adjacent (LOL---family members) show bits of the same qualities. I like to say that my son's DNA collected every quirk in the family tree. As a result, he is a marvel: simultaneously exhausting and awesome. I'm watching for future books about Lift. I've got my eye on her awesomeness. ;-) Sazed did not come across as having autism to me. Once you remember that his metalminds gave him access to an abundance of information and that he is a eunuch, a lot of his personality falls in line with that of a neurotypical Terrisman. The fact that I just wrote neurotypical Terrisman strikes me as hilarious. I mean, it's a Terrisman, which is not exactly the same as human therefore what is the typical nature of their neurology? <- And there is a bit of my quirkiness coming out. :-D As to the description of autism being a difference or a disability, I think it just depends on the extent to which it affects your ability to live independently. For those who live on their own, hold down a job, have a family, etc... it's merely a difference. I do not think it is a disease. It is fundamentally an information processing difference that can result in scattered skills, developmental delays and savant abilities. It's a grab bag: you never know what you will get. Trying to raise a child with the diagnosis to survive in "the wild" is never boring.