God never unleashed His wrath without provocation.
What possible provocation makes genocide moral? How did the children and infants of those peoples provoke God?
Sorry, but 'they had it coming' is one of the most immoral justifications for ANY action.
Face it. The God of the Bible picks and chooses what is 'moral' from moment to moment. There is no hint of constancy, let alone anything like the 'absolute' you keep trying to tout.