In most cases when someone is called a black "expletive" it is offensive as it is usually intended to portray someone is an "expletive" because they are black. How often have you been called a white "expletive" by a fellow white? I'll bet its nowhere near as often as most blacks have been called a black "expletive" by non-blacks.
And I am not sure what the comment has to do with the current discussion as there is no suggestion Symonds has been called a black anything. The allegation was that he was called a monkey, and that it was intended as an insult of his racial background.