The white people around dude knew he was wrong and let him get roughed up a little. In college I had situations like these come up because people will test you by saying it once. 95% of the time when I checked them on it they would hit the Cenk Uygur smiley and fall back but every once in a while one or two of them would try to argue about it.
Once during the Super Bowl this cac was saying ****** so I said to him 'what did you say?' and instead of saying 'my bad' he went off an huge tangent that he must have had at the ready about how he should be allowed to say it. He started going on and on all the white supremacist talking points we've all heard before (you guys say it, its just a word! what about Obama?!? white people dont get scholarships!) and I shut down all of his points, instead of being an adult and saying sorry or anything dude went outside fuming and probably saying it some more.
A few weeks later, the dude is getting ready to go to his parents condo in Mexico for Spring Break. He goes to a bar, gets in an argument (probably said some more slurs) and ends up getting his face rearranged so badly his jaw was wired shut and he couldnt go anywhere for two weeks. I don't know exactly what happened but to me it was just more evidence that karma is real and will get you back when you least want it to.