See, why would you do that?
You are carefully constructing an interpretation of the Bible that is tied to an historic event. You try to construct a logical argument that says if the history is wrong then the whole of Christianity is bunk.
You sound just like some of the more militant atheists here.
Now you might use that logic to convince a number of people. Then they finally see enough evidence (maybe more is discoverd) and see that some of the history IS in fact wrong. What have you done?
What are you risking here?
The commandments can stand on their own. The story around them is saying they are given directly by the hand of God. There doesn't have to be anymore than that. THAT is the important message. The rest is just pretty wrapping for the folks millennia ago.