Well, I’m glad you don’t feel that way, your approach was a bit confusing though. While the law against Adultery was clearly found in the Law of Moses, there were other laws, not had by us now, to which Joseph referred when he said this:
Gen. 39:9 because thou art his wife: how then can I do this great wickedness, and sin against God?
God is the same.
It's too bad that Joseph Smith did not feel this way when HE took OTHER MENS WIVES!
Clearly Joseph understood that to do this was adultery - to take some one else's wife. This is an entirely different issue than polygamy. It appears that this Joseph had the moral awareness that another Joseph didn't in the 1800's when he took wives of other men to be his own.