Meh, much of his work is in the the gangster genre, and the last two films were set in 1800's America. Guess what, the word nigge-r, nigg-a, and tons of other vulgarities flew in those worlds. I suppose because his stuff is on the pulpier side of the spectrum, sites like Gawker, etc.... feel more comfortable taking him for task for it.
The man's vision, is the man's vision. He should be able to express it freely.