I think he saying there was no right morally, then again who knows what's going on in that dense communist skull of his.You did until they took it away. Educate yourself.
I like how he says "you" as if to infer you are guilty of slavery. He probably doesn't realize rightly or wrongly that slavery has been practiced at one time or another by almost every nation on Earth and that historical fact was the only "precedent" needed.