Whether you think it’s all right for South Carolina to fly a Confederate battle flag over a Confederate memorial on its capitol grounds depends on whether you think that the Confederate war dead should be honored. If you do, then you can, as David French does, see the flag as a symbol of their valor and skill while decrying its use by white supremacists.
This strikes me as a whitewash of both the flag and the Confederacy. The Confederacy was a rebellion founded on the incoherent idea that the sovereign authority of the United States might be shucked off at the states’ pleasure, and the Confederacy’s primary reason for being was to preserve racial slavery — that is, to violate natural rights rather than to secure them. That is what Confederate soldiers fought for. Whatever else their battle flag may mean, it has to mean that. It did not become a banner of white supremacy in the mid 20th century when racial segregationists took it up. It was a banner of white supremacy, and of lawlessness, from the beginning.
And that is more than enough to disqualify it from respectability. Valor and skill deployed in the service of evil do not deserve honor. If your ancestors fought for the Confederacy, I do not respect their “service” or their “sacrifice.” I can accept that some of them may not have grasped the enormity of the Confederate project, and so are not to be blamed personally, but neither should they be celebrated. Citizens of the nation they rebelled against should consider it a breach of civic manners to display with sympathy the symbols of their cause. And there simply should not exist memorials specifically to Confederate soldiers. The telling of history does not require them. There should be memorials, rather, of the Civil War, with the American flag flying over them.