I don't see how having a disability would have any effect on a Sim's ability to use supernatural powers. My Deaf character I mentioned in the other thread is a vampire, and if anyone offered to "cure" her, she'd be super mad at them. She likes herself the way she is. (She was also a plant Sim at one point, but that's a whole different story.)
Advanced technology doesn't automatically mean disability doesn't exist. (I recently read a science fiction anthology called Accessing the Future, which solely featured disabled protagonists and not a single "cure" story.)