"As for the boys they would have died anyway because there would be no one to look after them. Given the option of a slow death from hunger and thirst, clearly God chose the merciful option of a quick death. All the cattle had been taken as booty. Had he allowed them to live among the Israelites they would take revenge later when they became men. If you're going to do the job do it right. The Moabites would probably have used the boys for child sacrifice (by fire) as was their practice."
Either this apologist does not understand the concept of omnipotence, or he doesn't think God has that quality. I can think of several solutions that an omnipotent deity would have the power to effect.
- Teleport the Midianites to an earth-like planet in another galaxy, sending angels to care for them till they are older.
- Soften the Midianite boys' hearts (like he did to Pharoah, but backwards) so they wouldn't take revenge.
- Send his son thousands of years earlier, bringing the message of salvation to the Midianites before they became a problem.