The norm, inherently neutral, and objective

Why were so many GOP senators so concerned about Sotomayor's "wise Latina" comment? Eugene Robinson in the Washington Post suggests that it's because straight white males perceive themselves as not having any ethnicity, they are the norm and inherently neutral. Anything else -- female, gay, brown, black, etc. -- must be compared against this "objective" standard. Farfetched? Alito was asked about his background and it was considered no consequence. Sotomayor's background, however, is fretted over because it might exert too much influence on her rulings.