I acknowledge and employ the problem of forming a medical diagnosis when the patient cannot be directly examined and when I am not a doctor
. All of the following will be merely a lay person's opinion and intuition.
I suspect that the Prophet Muhammad may have been significantly far along the autism spectrum. I base this entirely on anecdotes.
The basic diagnostic criteria listed in the sections relating to Autism Spectrum Disorder in the DSM V and the ICD 11 are deficits in social communication and restrictive and repetitive patterns of behaviour, interests, or activities. An autistic person can be sociable enough to become successful in business as Muhammad was but his stereotypical behaviours give him away. He could spend days in a cave ritually kneeling and prostrating. The form of ritual Islamic prayer as it is today is based on the repetitive movements that caused Muhammad's religious experiences.
Autistic people are also known to be iconoclastic and this Muhammad literally was since he converted the temple at the Kaaba into a mosque.
Autistic people are supposed to have poor theory of mind and while I personally find the psychopathic autism theory disgusting at a number of levels I am not the one to be arguing with the world's leading experts on the matter. Anyone who has read the Qur'an will have gotten the same impression from it as I had which is that its author assumes that the reader knows everything the author knows and context never has to be explained. The author of the Qur'an tells stories the way a toddler would when they have not learnt to explain themselves. Hence the vast diversity of interpretations of the Qur'an among Muslims.
Autistic people develop obsessions for their objects of interest. For Muhammad that was God. They also expect punctuality and rigid observance of rules. Muhammad designed a clockwork daily ritual regimen. That might be all that supports the argument but it is more than any of the counter arguments.