Robert Farley is appalled that Kentucky may soon offer Confederate license plates, in honor of those who betrayed their country so that white people might be able to own blacks as property. Farley points out that Kentuckians mostly fought for the Union, so it's odd that symbols of the Lost Cause would have resonance.
I think the ongoing prevalence of Lost Cause mythology has something to do with the structural impediments Matthew Yglesias described to Democrats becoming the "party of national security" in the aftermath of Osama bin Laden's death.
I'm much closer to Ben Adler’s pre-rebuttal of this idea which argues that it’s really all about rhetoric and identity politics, but I’d sort of go even further than this. The basic asymmetry is that Republicans are the party of America’s white Christian ethno-cultural mainstream. Of course atheists, Jews, Muslims, and Buddhists complain when someone says “America is a Christian country” but the claim at least parses correctly. We all know what that means. And we know why it is that “minorities” is a word that also means “people substantially descended from non-Europeans. The definition of authentic mainstream Americanness has shifted over time in our history (it now clearly includes Catholics in a way that it didn’t 100 years ago) and will continue to shift in the future. But the party of the mainstream has a clear and obvious edge in seizing the mantle of American nationalism, and thereby “toughness.”
The basic point here is that American nationalism is distinct from patriotism in that it embraces a certain problematic ethnic subtext about what being "really American" means. So that's why lionizing "treason in defense of slavery" has yet to take on the toxic qualities of say, being associated with The New Black Panther Party, because to many conservative nationalists, the latter is actual betrayal and the former is just a more honest expression of loyalty.