When rescuing Halsin, whatever players do with them is players' own decision, but Halsin, on storytelling wise, who is not a shadow druid, shouldn't be the one who would willingly harm those goblin kids in a deadly way. This fight reminds me of the owlbear fight, if Halsin was in players' position fighting those two owlbears, would he decide to kill that owlbear cub? Of which I think not. And since druid are able to talk to an owlbear, while both owlbear and goblin are capable to kill humanoid beings without moral trouble to them, then what's the difference between an owlbear cub and a goblin kid?
As already mentioned, an Owlbear is a monstrosity created by magic, it's not a natural beast, it's an incredibly aggressive monster that will eat any living creature, and absolutely has the potential to upset a local ecosystem.
Hmm, there is no united conformation on the origins of the owlbear(in lore, in real life we know Gygax based it on a toy). Dragons and other monsters are also magical creatures but still considered to be parts of nature in Faerûn. So a druid being against its existence just based on that feels wrong.
That said, druids are champions and protectors of natural order, not life only, so if having to kill one to uphold the balance would seem like the necessary thing to do, a druid shouldn't hesitate IF no other options are available. Being true neutral(if we're going with the archaic alignment system) don't mean being passive and even a druid can and will make mistakes in his/her life. You know the saying; the one who pokes a bear rarely lives long enough to tell about it.
Went abit off there but my point was that I agree with Halsin killing the children or potentially an owlbear, just not because of reasons stated by others above.
