He is , I think he literally has genius level IQ or something very close , yet still available to communicate on a "normal" level.
Off-topic but that's exactly what (part of at least) being really smart is all about: being able to explain very complicated matters in layman's terms so that everyone understands.
You have to be careful what you choose to believe in life because there's a major difference between a really intelligent human being and someone who's simply good at making him-/herself SOUND smart...(mostly by using a lot of jargon which makes the uninformed go "whoa, he/she is using all these fancy terms, he/she must know a lot")
I've seen a lot of the above in the BB-industry. (And in all walks of life)
If I'm not mistaken, Justin Harris is a physics-engineer by education so that basically automatically makes him very, very intelligent. Doesn't have anything to do with BB'ING per se but at least I'm assured of him being able to THINK rationally.
On-topic: I don't like giving my health/PED-regimen out of my hands but if I would do so, I would definitely go with someone like Justin Harris for that. (Him being as intelligent as he is would be my main motivation for choosing him)
Not implying the other coaches mentioned aren't good or health-conscious just to be clear, I don't know much about them so I can't comment there.
To give just 1 example: I once read a post by Jansen that was full of grammatical errors and they weren't typos. If someone can't properly communicate in their native language then I have to question their overall intelligence. Would I want someone like that in charge of my PED-regimen? No fucking way.
Sorry for my long and somewhat off-topic dissertation, I felt like giving one