In other words, that we can speak of them does not therefore imply that they are reducible to the grammar or logic of our language-games. Such a transaction is, of course, a logical fallacy. BTW, the existence of such an observer does not necessarily entail being spared, even in theory, from the trauma of ethical uncertainty. I disagree that realism necessarily imposes some sort of artificial clarity or certainty in ethical dilemmas. As W reminds us in a quite different context, but illuminating here as well, there are not rules for our use of language that are so 'precise' that they prohibit all doubt in all situations.
Ethical concepts have a grammar unique to themselves.
W. enjoins us to not think, not to repose in our ivory tower fancies, but rather to look, look at that diversity, a diversity which is overlooked by our theorizing. There is no 'ethical reality' 'out there' for us to discover, to think that is to adopt a physicalist or scientistic analogy of moral truth. It seems to me that this statement betrays the exception granted to science, as having privileged access to reality per se, even if indirectly, if for no other reason than the acceleration and proliferation of technology, which so manifestly shapes our world, is fueled by a science that presupposes a basic realism. We cannot deny that science as practiced seems to work. It would seem that this dualism of the early W persists in many thinkers today.