Aren't we confident. Brushing off 30 years of experimental research on the subject just like this....
Garbage in, garbage out. 30 years of experiments on a flawed theoretical framework is worthless - those experiments are just more bulk in the Augean stables. Conservatives like his theory because he - in his cognitive mode - believes that conservatives "see" a value that liberals don't. (putting aside that his view of conservative / liberal is another pile in the stable of his lab) But he completely ignores that leftists 'see' purity and explicitly reject it. Because, you know, they see but oppose attempts to purify a nation . . .
Edit: There are factors in Faerun there aren't present in the real world. There are no atheists in Faerun - the afterlife is reality. Your actions on Toril literally change the outer planes. Gods reward or punish for making certain decisions. All of these factors are missing from modern theories of morality. Which is why - if you were to do it - I think Plato would be best because it has the metaphysical aspects you need for a moral theory to work in the Forgotten Realms. (and, to a lesser extent, so does Kant)