A person without legs does not stop being disabled because they have no need or desire to walk. The fact remains that should they need or desire to walk in the future the hinderance will still very much exist.

A similar example could be made of someone with gluten intolerance. If they do not eat foods that contain gluten they are still gluten intolerant. They are however still disabled by needing to stay in that situation.

Ah yes, but that results in two problems.

Firstly a fish without legs objectively does not have legs, but we do not necessarily call it disabled, even though it clearly lacks a facility.

Secondly, the autism spectrum disorders are, as I previously mentioned, not obviously just about deficits of behaviours or functions but also can take in extended and exceptional abilities in some areas and greater sensitivities rather than deficits or lack of an ability, so it is not clear that the entire diagnosis can be defined by deficits or lacking things. The high functioning and Asperger's type diagnosis is not about a universal deficit diagnosis and we do not generally call neuro-typical humans disabled because they lack prodigious activity or interest in math, language, or other subjects, even though that can also objectively be measured and called a deficit.