The estimated population probably doesn’t take into account a literalist interpretation of Genesis, so perhaps not relevant to an evaluation of Genesis in its own terms. I’m not saying the figures make the difference but your specifying the numbers does make one wonder why you introduced the specific number as well as on what basis.
I am questioning the ethics of theoretical discussion about God’s culpability for mass killing in a context that we can’t fully understand if it did happen, rather than focussing on our own complicity here and now in a mass killing we have no excuse for remaining ignorant or indifferent about.