Adam Serwer lays out conservative allegiance to the Bender theory of discrimination, namely, that the only type of discrimination worth talking about (or even noticing, really) is the kind that affects them. Since most Republicans are White men, this means a huge emphasis on how White guys can't catch a break in modern America. But on the rare occasion that a female or non-White Republican catches hell, then suddenly racism and sexism become a problem. But only then -- it's not like seeing sexist attacks on Sarah Palin suddenly makes them realize launching them against Sonia Sotomayor is wrong or anything.
They also, I have to add, play the game badly, mostly because they believe their own rhetoric about how "discrimination" is nothing but politically-motivated whining. That being the case, they're happy to engage in it when it helps their own political motivations -- but they don't seem to grasp that a discrimination claim actually does have to have some content. So while Sarah Palin certainly did face some sexism, it is clearly untrue that all the troubles she faced could be traced to it (as opposed to the far greater contributor -- her own massive incompetence and egomania).