At least Templars probably didn't blow up non-mage children just because they might make people LIKE mages a little more.

"Then in a way, I'm sorry you're here, instead of fighting the fight you're needed for back home," David answers, because he can respect pretty much all of what Anders said. He does, slightly, fear what 'getting rid of' would mean, but given Anders said his world and time was a bit like this ren faire... well, there probably wasn't another way.