And I Say This As a Southerner...

I'm not sure if Chief Justice John Roberts was merely trying to get the Solicitor General to say something impolitic, or if he is really that oblivious to real-world circumstances, but this is not a debatable proposition:

“Is it the government’s submission that the citizens in the South are more racist than the citizens in the North?” Roberts asked.

There is real public opinion data on this topic. Whether you look at immigration, positive vs negative views of African-Americans, actual incidents of discrimination--Southernors has substantially more retrograde views on race than residents of the Northeast, West, or Midwest. This is not to say racism is confined to the South, just that it's more prevalent there. You could argue that picking on the South is counterproductive at this point, and that instead the Federal Government should adopt a more carrots/fewer sticks approach to dealing with racial discrimination and its unfortunate legacy. But I don't see how anyone living in the Reality-based community can arrive at any other conclusion when it comes to the public's views on race.

I wouldn't even be surprised if Roberts encountered Southerners who did not exhibit much racial animosity when he was a federal judge or corporate lawyer. But of course these are quite obviously exceptions and not the rule.