I've never managed to understand this when it comes to autism. Autism used to be considered something as extreme as a severe disability (e.g. Rain Man), and latterly with the inclusion of Asperger's into the spectrum, at the very least a collection of undesirable behavioural characteristics. Do people really want to be diagnosed with something wrong with them, or has the perception of autism shifted to at least neutral (if not positive)?
It may genuinely be that their dog is their emotional support, but it's ultimately a bit of selfishness and wanting to be treated preferentially in a world that feels crowded and rigid.