Well, he might be taking classes through an online program, or something. I gather that the superlative relates to his GPA, not rank (In most schools, I think the titles often have to do with discrete GPA, not ranking position. And I also agree that I don’t connect them with HS, though maybe private HS’s use them.)
Be that as it may, we don’t have Publix in our area, but whenever I see “Publix”, to me that name looks like something that could be censored!