This is actually a good point. There were actually quite a few supporters of the South in the North during the Civil War. Why? Not because they supported slavery, they did NOT. It was because you can't have a "Union" unless there was the right to succeed. Many of the supporters in the North supported the South because if the government became too oppressive, they too wanted the right to succeed.
While to many, the Confederate Flag represents states rights, Southern heritage, the right to rebel (against whatever), the fact of the matter is that the Confederate Flag now represents racism to the vast majority of people. The supporters of the CF are fighting a losing battle. This is just like the swastika that was originally a Jewish and Middle Eastern symbol and was used throughout early Judaism in a lot of artwork and on stone ostuaries (stone "coffins" just for the bones). Today, it represents Nazis no matter how much the swastika supporters might want it to be a religious symbol.
At the same time, Amazon, Google, etc. apparently are ok with selling Nazi flags and other memorabilia as well as T-Shirts with the face of the Butcher of La Cabania (Che Guevara), Pol Pot, Mau Tse Tung, Stalin (who killed more than Hitler ever did), etc. If they are going to remove something like the Confederate Flag, they should be even handed among all the people who have murdered millions and persecuted even more.