I have never heard the term "blink" used to describe someone with a disability. It might refer to someone with something like Tourette's Syndrome who has uncontrollable facial tics and perhaps blinks a lot, or maybe it refers to blind people. I found the book that's the source of this quote on Google Books and I see it was copyrighted 20 years ago, so maybe it was current slang at the time, but didn't last long.