As I side note, I'd like to say I'd imagine nearly all political beliefs throughout history have had people citing every imaginable form of ethics as justifications, and furthermore without even distinguishing between them. From what I understand the vast majority of people don't even realize there's a distinction (I myself didn't know about non-consequentalist ideas until about 6 months ago, actually).

BTW, I would say that an argument about "the freedom to own slaves" is essentially an argument that slavery being allowed is a terminal value, although I'd doubt anyone would argue that owning of slaves is itself a terminal value.