I think you may not be familiar with how "sellout" is commonly used. It's commonly said, e.g., of musicians when they make a popular song, for violating their assumed allegiance to being "true" to something other than career. It's more about an abstract idea of what someone or something "stood for" than about the actual person, and it takes place in the minds of observers more than anything.

I don't think what he does in his work for Apple has anything to do with it. If he tried to go back to the Anandtech style of journalism, I think he would lack credibility now that he has accepted a job at Apple.