Yes, we can put whatever odious symbols on our products.
The Confederate flag is a bit weird because there's enough of the population that apparently doesn't see it that way, so some stores will even display products that have it. (Personally I find it to be an awful symbol and wouldn't stick around if I saw it displayed).
An example that is more like what you've described is something like a Nazi swastika -- technically you can sell something with a swastika on it (I'm 99.9% sure) but almost no stores would be willing to put it on the shelves, certainly no major chains or whatever.
The Confederate flag is a bit weird because there's enough of the population that apparently doesn't see it that way, so some stores will even display products that have it. (Personally I find it to be an awful symbol and wouldn't stick around if I saw it displayed).
An example that is more like what you've described is something like a Nazi swastika -- technically you can sell something with a swastika on it (I'm 99.9% sure) but almost no stores would be willing to put it on the shelves, certainly no major chains or whatever.