+1 for consistency: if the game allows us to kill goblin kids, it should also allow us to kill human or tiefling kids. If we can't kill human kids, we shouldn't be allowed to kill goblin kids.
+1 for people in BG3 having different thoughts on what counts as a monster. Goblins are commonly thought of as monsters in D&D, so it's perfectly reasonable that Halsin is fine killing goblin but not tiefling kids. Others may consider tieflings monsters, and thus would be fine killing tiefling or goblin kids. Having both those views (and more) present in the game, where your party can experience and navigate through those views could add an interesting dimension to BG3's world and roleplaying...if done well. - E.g., you can kill all kids, but while Kagha is fine with you killing tiefling kids, Halsin disapproves and maybe even goes hostile. And both of them obviously won't tolerate killing of human/elven kids.
