EDIT: Okay, I sort of see your point. My feeling is that if you consistently work long hours you definitionally put yourself outside of the "social mainstream," because I was thinking of "social mainstream" as "the set of people whose non-work lives are fairly similar to the median".
Whereas I think you're using a definition closer to "people who aren't 'weird'/'losers'". I don't think that's what the original commenter meant, but it's possible. And if that's what he meant, I think you could be right.
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For the record, I don't (necessarily) agree that geeky people are more likely to do good computer work than non-geeky people. I just think that it's a valid point of discussion, and that in particular comparing the quoted comment to racism instead of addressing it is both incorrect and incredibly obnoxious.