Rather the point was that children sometimes suffer as a result of what their parents do. Here is an analogy: on September 11th, as those 'planes hurtled towards the World Trade Center and the Pentagon, there were probably some babies and children on board. Those children had not done anything wrong that caused them to be there. But if the American Government had been able to respond fast enough and decisively enough, I am fairly sure they would have shot the planes down before they could be flown into the Pentagon and the World Trade Center.
Does this mean that the American Government condones the killing of babies and children? Surely not. The point is that the threat would have been large enough and serious enough for them to take drastic action, and because of this drastic action, innocent children would have died.
I believe that this is what was going on when the Israelites destroyed the Canaanites. One of the reasons we find it difficult to see it this way is that we do not take seriously enough the evil these nations were doing, or the threat they posed to God's good purposes for the whole world
What utterly ridiculous reasoning.