If you understand the concept of the broad autism phenotype (BAP), it is hard not to see it in his behaviour. He obviously has autistic traits.
Now, is it BAP (sub-clinical ASD) or is it clinical ASD? Nobody can answer that unless they are actually a qualified diagnostician (psychiatrist/psychologist/etc) personally evaluating him.
But I'm not sure how much that matters. The boundary between BAP and ASD is vague, it varies from clinician to clinician and is changing over time.
If you choose to view things dimensionally [0] rather than categorically, you have "super-neurotypical" people at one extreme, you have "severe ASD" at the other [1]. And somewhere in between the two, you draw a line (the diagnostic cutoff), and say people on one side of the line have "mild ASD" and people on the other side of the line don't have ASD. And the people who are on the "neurotypical" side of the line, but still close to it rather than far away, that's BAP.
And I think the point is that RMS obviously is somewhere near that line, whichever side of it he may belong on. (And as I said, the line doesn't have a single fixed location anyway, he might be on one side given some clinicians' ways of drawing it and on the other given others'.)
[0] I've drawn an oversimplified one-dimensional model here. In reality ASD is a multidimensional construct. But, treating it one-dimensionally is a simplification which aids in explanation
[1] I know some people don't like phrases like "mild ASD" or "severe ASD" (or their close relatives "low functioning" and "high functioning"), but how else do you explain the difference between someone diagnosed with "ASD Level 1 / Level 1 without intellectual or language impairment" and someone else who is diagnosed with "ASD Level 3 / Level 3 with intellectual impairment and language impairment"?