DOES GOD WANT CHILDREN TO PERISH?

Matthew 18:14 Even so it is not the will of your Father which is in heaven, that one of these little ones should perish. Critics, of course, point to times when God killed children (such as with Noah's flood) or ordered their execution (such as with the Amalekites).  If God didn't want them to perish, why did He do those things?

God wants all children to be with Him in Heaven.  If (as many believe) all children do go to Heaven upon death, then those God killed or ordered killed joined Him in Heaven, and thus did not perish.  If (as others believe) children of wicked heritages don't go to Heaven upon death, then God (being omniscient) knew that these children would not end up saved, and would perish no matter what He did.  If so, His ending of their lives only brought about the inevitable.  They were going to perish anyways, so God ended their lives sooner in order to prevent them from doing harm to Noah's family or the Israelites.  Not a contradiction.