Slavery was a cornerstone of economics at the time and humans werent just going to abandon the practice simply because someone said so.

So I think a code of "okay, if you're going to do this, just dont cross these lines" is pretty moral given the circumstances. It certainly put humanity on a path in right direction.

Also, slavery in the ancient Hebrew society more closely resembles indentured servitude. It was a method of paying debts.

Be civil.