Sorry Bilbo, but I'm afraid whilst the comment in of itself isn't high on the racist scale, what it does do is suggest something about the man behind the words and the implication that he believes himself to be better than any white man to ever pull on boxing gloves. And in that, he rules out the possibility that any white man could be better than him, which is racist.

In terms of scale of racism, it is close to one one the one to ten scale of severity, but it still is racist.

AS for

Quote Originally Posted by Bilbo
Real racism involves the subjection of one group of people by another, treatment of brutality, of slavery, of intimidation and hostility. It involves the taking away the rights of one race by another.
I can't see how it would need to reach such a scale to become racist, surely just a comment about a p**i at the corner store or a n****r is racist, and doesn't involve any of your description.