In practice, it seems that whenever someone is told to shut up for using the N- word, they react by saying it many more times. So it doesn't work very well.

> whenever someone is told to shut up for using the N- word, they react by saying it many more times

One, not my experience. (Indian family.) Two, people spouting out the N- word have generally caused themselves to be ignored, which sort of solves the problem as well.