I have heard they are already getting fans asking about how far this rule goes. Like can they wear shirts with the flag on it. Or what if you have a confederate flag tattoo. That sort of thing. Seems NASCAR is fine with tattoos (duh, they have to be) and so far I heard as long as the flag isn't the prominent part of your clothing, then that's OK too. So Dukes of Hazard shirts are OK but a confederate flag turned shirt is not.
I'm sure many will push those boundaries. And try to exploit all edge case grey areas.