The worldship is a viable military target. It is used to transport soldiers for planetary assault and used by them for quarters. If the Vong government doesn't care enough about their kids to put them on a military target can the GFFA care more and avoid firing upon military targets - of course we can't do that. We have to fight back. And it hasn't even been said for sure that kids were on that ship. There are no Vong civilians in the GFFA. All Vong are there illegally by force of their warships and they have killed trillions and even destroyed a few planets. And in wars civilians do die. Some innocents die. It's unavoidable. How many engineers were on the Death Stars? Lots.