Never said polluted, just overrun // read my words.
I also find the complaint that the battlefield is overrun with monuments to be strange. It's like objecting to all of the tombstones in a cemetary.
As far as the idiot who is undertaking this stupid publicity stunt, we can all be pretty sure he wouldn't have had the stones to fight under either flag in 1863. If the guy wants to protest that flag, do it at the capitol of a Southern State, not at an honored battlefield.