Autism exists on a spectrum. A spectrum that includes “normal”. Many of the traits and behaviours which are used to define a diagnosis of autism are also experienced by people that wouldn’t fulfil the criteria for a diagnosis. If, for example, they don’t cause any problems for the individual experiencing them, at work or at home. I presume that’s what he means and it’s true.
It's not 'A' spectrum, it's a Autism(!) spectrum. It's named that way because people on the spectrum have Autism.
The name is changed(since 10 years)to a spectrum because many sub forms of autism overlap