It is ironic that the people that are so often on the right side of power divides are completely blind to the cultural and class prejudice that makes shitting on southerners socially acceptable.
To be clear, I'm gay and have no love for the Confederate Flag, but you have to realize that making fun of rednecks is definitely Punching Down, not Punching Up.
I'd imagine for Black Americans it's punching up and they shouldn't feel bad about it. After all, America at large has been punching down on them since the inception of your country (not that my country is any better, but this isn't about my country).