I would use caution in making armchair diagnoses like that. However, while we are throwing around psychological terms, I do believe that "anal-retentive personality" is quite apt.
I'm not sure either applied, as least from the four or five reviews that I read in great depth. His reviews were opinionated, and touched on themes that he though were important - but by and large weren't overly detailed or comprehensive. He sought to capture the overall arc of the growth of OS X, rather than regurgitate every new feature.
I believe you're misreading this. He isn't trying to imply Siracusa has autism, but rather is implying that the level of detail in his reviews is similar to what one might expect of someone who does have autism. This is a significant difference.
I would use caution in making armchair diagnoses like that. However, while we are throwing around psychological terms, I do believe that "anal-retentive personality" is quite apt.