please don't think I'm taking up for this guy, nor that I agree with the juvenille comment BUT, are you assuming he's white and talking about blacks?
More than likely, he was saying that only blacks "shank" people and he is just guessing that the poster is white. Methinks that it was "tongue-in-cheek" but I could be wrong. There has been alot of BS supposedly "racist" coments floating around FI lately that are just BS. People are just way too sensitive.