Goodness grief, keyboards at dawn eh?
I reckon it would be foolish to think that dealing out an elbow to the head of some yob is going to teach them a lesson... they are probably used to violence, and if anything it'll just increase fuel their racist behaviour, because that's the way those small-minded, pea-brained people work.
Yeah at the end of the day the scrote probably deserved a good kicking, but then again he's probably taken a good few over the years and lives in a culture of violence, so all your mate did by elbowing him in the head was act like a **** himself, and all you showed him once more is that violence works, and he'll take it out some poor and unlucky sod at some point in the future. If you or your friend think you have educated the yob in any way, shape or form about the finer points of how to treat ethnic minorite,s or increased his goodwill towards fellow man then you are deluding yourself. The elbow is far deadlier than the fist in close quarters, many martial arts use it with devestating effect but only when they want to REALLY hurt someone. Your mate is obviously as much a yob as they are and likes a good scrap.
Just my opinion.