The current debate in autism education is between those who assume competence, have expectations of intelligence, and as a result, frequently discover minds that think behind the autistic mask. The other school of thought is reflected in this statement by ASHA. That is, to assume competence is abusive somehow. I know what presuming incompetence does. It deadens hope and kills expectation. It makes seeing the ability impossible.
No one is claiming everyone is brilliant, just that fewer nonspeakers than the experts believe, are dumb. I prefer to believe that nonspeakers may have intellectual skills not immediately evident for a variety of reasons. See here for some reasons.
Look for intelligence and you discover more. Look for disability and you get stuck in limitations.
Please enjoy this Ted Talk on finding competence by Vaish Sarathy.