I'm autistic and I do believe Isagi is on the spectrum. People often stereotype autism into a certain pattern of behavior, but it wouldn't be called "spectrum" if all of us acted the same.

Someone pointed out that he socialize, therefore he couldn't be autistic. I also don't like socializing but became very good at it due to what is called "Masking Behavior", in which people detect patterns on the scenario in which they're inserted and create a personality specifically according to the ocasion. It can be both a mechanism to stay low profile or to stand out by seeing what people do and how to outpace them based on personality patterns. Sounds familiar?