"Think before you type" is a useful rule for anybody, including myself. On what basis do you infer that it could be intended as a "slur"? Your readiness to dig up any miserable morsel of insult in an archived copy of a pre-edited text reveals a paltry, morbid, prejudicial character. No, your unconvincing "irony" won't get you out of the trap that you prepared for yourself: humans in The Last Castle have enslaved the Meks. That makes this book "partially centered around two societies, one human and one alien, one of which has enslaved members of the other, to their mutual discomfort." And that is all I am saying, barring unsolicited interpreters of plain English.