I think because the south is more out with their racism. When you have a history of governors like Storm Thurmond and George Wallace winning elections by landslides because of their racist rhetoric it just promotes an unfortunate image.
Look at Ronald Reagan and Richard Nixon use of the " Southern Strategy". It was pretty much " those blacks are getting your stuff". What happens? They sweep the south in historic numbers.
Look at what Lyndon Johnson said after he signed the Civil rights bill. His quote was " I think we just lost the south for a generation".
I mean look at the state HBCU's in the south. All of them have a republican governor and Congress in charge of their funding. Every single one is losing money and resources. Look at Deleware state university. It's not the best school ( greatest homecoming amongst HBCU's), but there funding is much higher than other HBCU's. Little stuff like all of this, adds to the rhetoric that the south is more racist.
But to Be fair I don't trust any CAC, so it's whatever.