There must be hard and fast rules.
I agree that moral relativism is illusory, and that there are real ethical standards. On the other hand, if you insist that there are standards that are right for others, then you end up with something very much like the reilgious right, who seem overly concerned with how other people behave. Your statement about 'hard and fast rules' reminds me of that. America is a very fearful society at this time: scared of each other, scared of the world, and scared of the rate of change. I think this fear is driving a lot of the conservatism we are seeing. We desperately want to return to the good 'ol days when right was right, God was in his heaven, and John Wayne was sherriff.
I think the only resolution to the dilemma is that the individual needs to recognise ethical standards voluntarily, rather than having them imposed. A person needs to be intelligent enough to understand what is right and follow it, without having it imposed upon them. So I agree with your post in that sense: citizens must be recognised as responsible for their own actions. Only a small percentage of people may actually be able to voluntarily seek and practise that, but hopefully their influence will be disproportionate to their numbers. So, presumably, education should be aimed at instilling this sense of moral autonomy in individuals. I don't know if I see much of that in the cultural war between 'religious' and 'secular' views.
Incidentally, as regards the way in which quantum theory undermines the idea of absolute objectivity, I hope you don't regard this as a liberal conspiracy to destroy the American Way. Because it is a fact that QM does undermine the idea of absolute objectivity and naive realism. This does represent a crisis in Western philosophy, no question about that, and I don't think there is enough discussion of it, or awareness of what it means. My hope is that resolution of these very difficult issues will actually bring about a radically new understanding of the world and will have positive consequences, but that is far from certain at this time. The planet is in a pretty dire situation at this point.