If we strictly follow the Diagnostic Statistical Manual version IV-TR then a person is not diagnosable unless their symptoms are causing them difficulty. A person can have two-way conversations with a giant invisible bunny rabbit, but unless that is causing them difficulties then it is not diagnosable. Jackson was a successful general. If he did not see his quirks as problematic, and he was successful at what he did, I would not wish to ascribe any labels to him.
I assume you are talking strictly about Autism Spectrum Disorders, and not other pervasive developmental disorders or other mental disorders of the DSM-IVR? I interject only because my foster son was diagnosed with partial fetal alcohol syndrome at eight months of age. He met some of the physical characteristics common in individuals with FAS. Given those findings and the fact that his "egg donor" admitted to drinking during her pregnancy, a diagnosis was able to be made.
He exhibits very little of the behavioral traits common in a person with FAS, and developmentally he is caught up to his peers. Inside and out, he appears to be a pretty averagel little eighteen month old now. But most cognitive and behavioral deficits don't surface until a child becomes of school age. At that point, s/he is introduced to more abstract concepts and higher levels of executive functioning are expected.
Anyway, I know little about ASD. The breadth of my knowledge right now is wrapped up in FASD and FDSD.
It is an interesting speculation about Jackson. Frankly, it is equally within the realm of possibility and reason that perhaps he wasn't clinically disordered, but rather mentally gifted. We all have our ideosyncracies, our oddities and eccentricities. Jackson wasn't any different. He defied the concept of normal because "normal" doesn't really exist beyond the criminal or clinical. Say there are ten people in a group. If one person isn't similar to nine others--i.e., he zigs when the others zag--then he is considered different and not "normal" by the others. But what exactly is "normal" in this context anyway and who defines it? A significant part of what "normal" everyday behavior appears to be is perception and conformity.
Jackson was a brilliant strategist and militarist. He was one of a kind. Unique. God broke the mold when He made Stonewall. Can we not just leave it at that? Why must some folks decide that eccentricitiy equals a clinical disorder?
I like a clean kitchen and it bothers me to see dirty dishes in the sink. So, when I see these things, I feel a desire to wash the dishes and clean the counters. That may make me weird, but does it necessarily mean I've got OCD or OCPD? I think there is a lot more to a mental disorder than just eccentric behavior.