I am both reading and listening, I am just saying many people have the absolutist views of acceptance I described. The proof is the concepts of moral relativism I linked at Wikipedia; I know it is held in low regard by some, but I do not think someone wrote a whole article on a philosophy they only ALLEGE to exist despite its non-existence, or that such an article would have itself existed long if that were the case. I did not pull that cannibalism example out of the air as hyperbole; people have been discussing in terms of moral and cultural relativism for decades. Google it; when I did so just now I found, among many other discussions of it, an archived article from a 1986 edition of "Anthropology Today" in which a UVA antropology professor discusses it in terms of Michel Montaignes analyses of both cultural relativism and cannibalism half a millennium ago.

Beyond that, I really do not know what to say except that I have met, spoken with and in some cases known well people who argued quite sincerely that the morality of cannibalism and anything else you can imagine are wholly within the eye of the beholder. Beyond citing people who hold that view, some of whom even TEACH it in academic environments, I can think of no way to prove they exist. If real world examples are not adequate proof of their existence, what proof would you accept?