The Marines will be good for him. He sounds like he's has youthful errr...ignorance. Marines will turn him into a real man. Plus he'll meet different kinds of black people and I assume that the whole race thing falls away pretty quickly during the three months at Parris Island.
Generally, race relations in the military are much better than in the civilian world, but the guy who was causing trouble in my unit was a corporal with a few years in. Some people require a more direct approach.