He is kinda right, it's a dilemma:
Having a children in game improves the immersion, but the immersion is cut off the moment you realize they are essential.
So it's better not having any children, it's not like you are going to miss them.
It only kills immersion if you actually try to hurt a kid-or if you're just really bothered by the knowledge that the game won't let you even if you actually wanted to-which is kinda silly in my opinion.
As I said earlier there will hopefully be a more realistic way of making kids "essential" without making it seem unrealistic. It would make sense for them to run away and hide if someone tried to hurt them, if a creature or dragon has broken into town, or if somebody was going around on a murderous rampage-I don't think it would be too huge of a challenge to script the AI for children to behave that way. They might still technically have infinite hit points and there still might be some slightly unrealistic elements but to me it's worth the sacrifice to have the world fleshed out more with children.
If they are planning on including children (which judging from some bits of the GI article appears to be the case-either that or the examples involving children weren't at all based on anything they actually saw in the game), there's really nothing that's going to change that at this point. And there's little doubt that if they are included they probably won't be able to die (or at least they can't be killed directly by the player character)-we can only hope that the way they handle them being unable to get killed is handled in a way that does not totally kill immersion.