Randall is exploring Campbell's idea that maybe some times a slave is content to be a slave. Especially if he's under a benevolent master. Contrast that with for example a free man in a cold and uncaring society where might is right and every day may be a struggle just get food and shelter.

Campbell loved to explore such ideas, and I find them much more interesting than his obsession with the superiority of Mankind and "Psi".

The purpose of the story was probably to make you question wether concepts like "freedom" and slavery is as black and white (pun intended) as one usually thinks, and not a defense of racism.
But of course it assumes you are able to think in the first place, and not just feel.
Although the anagrams were rather tasteless, and cheapens what could have been a more subtle story so maybe your feelings are right.

Klaus J