No, as I understood it Saul was still alive when the Lord told Nathan to give his wives to David. I was mistaken. The bible talks about Saul's death in 2 Samuel 21 after the wife discussion in chapter 12. As I looked into it further however Saul is referenced as dying in 2 Samuel 1. When I googled the text the later reference is the one that came up.
If I am wrong on a point feel free to correct me and it will make us both better. Accusations that I am lying does neither of us any good. If I am wrong I will freely admit it and move on as I would expect the same of you.
The Ten Commandments are an expression of God's Holy nature ... He is not a murderer so 'thou shaltnot murder'; He is not an adulterer so 'thou shalt not commit adultery', and so on. The Israelites demand that Moses go ask God what they could do (they wanted to work their way to exaltation) to be righteous before God. Of course, lacking God's nature within them, they could not possibly live as equal to His exalted nature, reflected perfectly with the Commandments the people could not live up to 100%. That is the reason Christ took a tabernacle of flesh, dwelt among us as God with us, and gave His life/blood a ransom for our unrighteousness. Until you comprhend just how far from able to become exalted via even some tremendous works we humans are, you will not comprehend the unspeakable mercy and Grace of God in Christ Jesus.
That you would mistakenly believe God would go against His nature (He's not an adulterer so 'thou shalt not commit adultery') and give Saul's wives to David while Saul was yet alive tells us so much about the agenda of apologists willing to even contradict God's Holy Nature in order to make a place for smithism/Mormonism to exist in contradiction to God's nature.