Six months later
The whole of Children of Earth is riddled with this awful futility.
The aliens had no need to be there. Had they needed the kids to eat or breed, it would have been horrible yet in some way reasonable: everything needs to try to survive somehow. As it turned out, there was no need for Frobisher to take his final actions. There was no need for the government to seek out and destroy Torchwood (with all the collateral damage involved there — Rupesh, etc.).
Just about every problem in this story is a result of vanity or weakness of character. It’s just plain stupid chaos. Gwen’s taped message in episode five puts a bullet point on that. And that’s pretty interesting!
Something else to point out, thematically — it’s only Jack sacrificing his own that solves the problem. This, after five episodes of everyone saying “it’s okay; take theirs, but not mine!” Earlier even Jack had his moment, with Ianto. Until then effectively no one is willing to make a sacrifice, no one is willing to take the burden. Even for the best characters, on some level it’s someone else’s problem.
Which I think illustrates what a strong character Frobisher is meant to be through most of this — he takes on all the responsibility that no one else wants, and he handles it. Much of that responsibility is awful, and poorly judged, but he absorbs it anyway, and takes it all to heart. He kind of fails the final test, but by that point it’s hard to much blame him.
This all, I assume, ties back into most of the characters being civil servants. Sort of a sci-fi Ikiru, except with less annoying structure.