Eventually he even abandons his beliefs completely because a black person is nice to him? If he's suppose to be fairly intelligent this move makes no sense.
It's been a while since I saw this movie, but if I remember correctly he refused to interact with none white people entirely. At some point he realized that most of his skinhead fellows doesnt really care about the ideology and implemented a vast trade system in jail with other races. that was the point where the fight started - he lost protection from the skinheads and was even raped by one of them. at this point he questioned his entire attitude when he realized that the only person in jail, who prevented him from trouble was a black guy.
I believe that was the main statement here - race doesn't separate enemies from friends.