To be fair to him, his autism was only picked up on by the psychologist in the programme he did, rather than being something he'd suspected or being the thing he'd had the most difficulty with. It's possible he doesn't know how the autism impacted him because the ADHD aspect was 'louder' for him. He's probably still learning about how it all fits together into his childhood etc.
One of my children is a bit like that. His ADHD is really obvious but when he took medication for it (that didn't last long as he struggled taking it), his autism suddenly became really apparent.