Maybe it's because he's a bit of a gun nut on the side? He did some computer videos casually carrying a rifle of some kind slung over his shoulder.
I still enjoy his videos.
A lot of vintage restorers don't like him and people like him because he goes Wow! Look at This! and then suddenly a bunch of middle aged men with beards have that exact thing on their shelf. And those of us doing preservation and restoration suddenly are priced out of the hobby we've been in for decades.
Also, his technical "work" is not great. In fact, it's really bad. Even his successful fixes show a lack of attention to detail.
It's worth noting that he started his career as a computer scrapper.
Gun nut is fine. One can be a gun nut without supporting the awful ideas/people within that domain. It's the support of awful ideas/people in that domain them that make him "controversial" (a.k.a. anti-social asshole, that insist being an anti-social asshole is simply a personality trait, immune to criticism)
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I find it funny that being Texan == gun nut. But I'm from Oregon, lots of OreGUNians around here.