The preference is evidence that the "disability" really isn't, like homosexuality.

It can also be evidence that humans use 'sour grapes' as a coping mechanism.

Near one end of the spectrum of advantage, novel difference and unambiguous disorder is schizophrenia. There are those who declare that cognitive problem to be just a difference to be embraced or even something that can produce special success but I claim it is something that really is purely a negative thing. People can be successful despite schizophrenia, but not because of it. I would not make the same judgement with respect to, say, ADHD or Aspergers.

I am influenced, for example, by this Stanford lecture.