It's the lone hunter thesis.
There are biologic models of this. Killer whales come in a couple of varieties. First, there are the pods ~ much like any sea going mammal society, the pods cooperate in hunting, have family lives and friends, and are "friendly" to others who own very large steel hulled boats with massive engines.
Then there are the solitary killer whales. They are not friendly. They will even attack boats!
I did not suggest that it was.
I merely suggest that his hypothesis is testable. There are hunter gatherer societies in the modern world.
I do not see any individuals with but the mildest case of autism being able to survive in a hunter gatherer society. An individual with Asperger syndrome may be able to function in a hunter gatherer society but I very much doubt that a child with Rett’s disorder would survive in to adulthood.
Such a theory while interesting is not persuasive with out real world examples.