The Left continuing to rub out any and all symbolic and honorary references to the American Indian.
In ancient times, it was a common practice to remove the names of unpopular kings by chiseling their names out of the stone of their monuments, or ‘obliterating’ them. In more recent times, various totalitarian regimes have done the same thing to those who ran afoul of the regime. I think that any self-respecting Sioux would be very concerned about his erasure from popular culture.