Your response contains a good case for distinguishing between objective and subjective morality, but (IMHO) I don’t think you made it sufficiently clear. See if you agree with my interpretation of the events you cite.
At the time David coveted Uriah’s wife, he did not think it wrong because he was the King and his Will was law. In other words, he could establish the subjective morality for the culture over which he ruled. As David’s life turned to ashes, he began to realize that the objective morality, as stated in Moses’ Ten Commandments, took precedence, and thus 'thou shalt not commit adultery’ and ‘thou shalt not kill’ clearly labelled him as a serious sinner.
If David’s repentance was truly sincere, then God surely would have pardoned him regardless. But it didn’t hurt that God could foresee that David’s eloquence would result in the penitential Psalm 51, and that might help steer future generations from following David’s sinful path.
It still bothers me that so many ‘average’ readers of scripture see David as some sort of paragon rather than a horrible example of a moral code gone astray.
Al Leo