As for Enns when Piper says 'It's right for God to slaughter women and children anytime he pleases' I am amazed that this is not problematic for Piper. It certainly is for me.
That is not a God I could worship, or give my life to. If the nature of God requires us to support such a belief, then it is something I personally can't embrace. If God is like that then my short life would be spent set against such purposes and nature.
And by that I have no problem affirming that God is my creator, and he can spend and do with me as he wills. But an affirmation of the 'rightness' of God in capricious slaughter of innocents is a view of God that seems very far removed from the life and death of Jesus.
Enns takes Piper to task theologically, and most importantly pastorally doesn't leave us reducing God to a puppet who exists to confirm to our desires.
There are better ways to understand the genocides in the Old Testament, and Enns points us towards them.