The easy answer is that (unlike NBC, President Obama and apparently Judge Sotomayor herself) Republican senators are paying her the compliment of looking at her as an individual -- primarily as a judge -- rather than as simply some living composite of ethnic and gender characteristics.
The even easier answer is that as her nomination is considered, the GOP intends to treat Judge Sotomayor with the courtesy and the fairness that the Democrats denied Miguel Estrada.
In fact, as the press and the Democrats attempt to press the gender-ethnic angle, it's time that the GOP introduce the country to Miguel Estrada. He's the extraordinarily accomplished attorney, born in Honduras, whom President George W. Bush nominated to the US Court of Appeals for the DC Circuit (former judicial home of Justices Scalia, Thomas, Ginsburg and Roberts).
The Democrats took the unprecedented step of filibustering his nomination because in the words of Democrats themselves, "he is Latino" and they feared he was being groomed for a Supreme Court appointment.
This would be a wonderful time for Mr. Estrada -- now in private practice -- to make himself available for interviews. Citizens could compare and contrast him and Judge Sotomayor, and come to their own conclusions.