He feels surly

You're describing a gradient. That isn't what spectrum means. We all have a spectrum of symptoms - some kind of sensory processing issue, some kind of social interaction problems, some kind of repetitive motion issue, etc. Only when you have one issue in each category are you autistic.

I'm AuDhd myself - ADHD is comorbid with autism in a large percent of people. If you don't think it's a disability, you may still be in some denial about its effects on your life.