To the argument that the flag, as a symbol of the confederacy, (not whether it actually was at the time) could certainly be considered as a racial banner.
Alexander H Stephens, Vice President of the Conferacy : https://en.wikipedia.org/wiki/Alexander_H._Stephens
his speech March 21, 1861:
http://web.archive.org/web/20130822142313/http://teachingamericanhistory.org/library/document/cornerstone-speech/
the part that is of interest:
"Our new government is founded upon exactly the opposite idea; its foundations are laid, its corner- stone rests, upon the great truth that the negro is not equal to the white man; that slavery subordination to the superior race is his natural and normal condition. This, our new government, is the first, in the history of the world, based upon this great physical, philosophical, and moral truth."
Interesting read don't ya think?
To suggest that the battle flag of the confederacy is not as symbol of slavery is as stupid as saying the Nazi flag is a symbol of a part of German history, and not racism. Both do reflect the heritage of their respective societies---and those societies were based on pure evil. They are not the heritages that need to venerated. They properly should be used to show how horrid societies can become.