If we parse that statement, perhaps it means something like "In the past, black athletes have been kept out of the QB position because they were considered too dumb to learn the complex playbook, or because they were thought unable to exercise leadership. That sort of bias seems to be disappearing since having both finalist teams led by black QBs indicates times are changing."

But why should saying that be a double standard? Or conversely, why should it indicate your liberal friend is a hypocritical bigot?

The term "hard-hat" has always been used, on both sides of the political aisle, to denote a blue collar individual who favored Nixon and America's participation in Vietnam, and who was critical of the politics and ideas of the Liberal Left (particularly as expressed by long-haired hippie college kids in the 1960s.) It was never used to attack working class people just because they were working class. But the Right has always accused the Left of their own crimes and shortcomings as a distraction. Similarly, "white trash" was what aristocratic and prosperous Southerners called their proletarian brothers. The Left did not invent that term either.