By applying the term "racial abuse" to what Gazza did you are doing a disservice to people who have actually suffered racial abuse in their lives.
I think Mrs R's point is that if Gazza had made the "flattened some grass" joke then we wouldn't be hearing about it now, it wouldn't be in the press and it certainly wouldn't have made it to court.
What if the security guard was a Frenchman and Gazza made some allusion to "frog's legs" or "snails"? Nobody would have batted an eye. It would appear that some people's feelings are worth more than others.
So just for a second, lets take colour, race and religion out of the equation and just say that out of the whole population there are some people that you can safely make jokes about, but there are some that are off limits for one reason or another. That in itself is a form of discrimination that can only eventually lead to animosity.
Treating only certain sections of society with kid gloves is the opposite of the equality the politically correct claim to seek.
In future it would better if whilst deciding where to put the line between a joke and what you've called "racial abuse" is that the first place we look is at the intent of the person who delivered it and in this instance, poor though the joke was, somehow I don't think Gazza's intent was to denigrate an entire race of people with it.