"Jack cared for his grandson." And we all know how that turned out. Intent is meaningless; the best laid schemes o' Time Lords an' men gang aft agley. It's bad enough that the girl is trapped in this universe, trapped in Manhattan, surrounded by rifties of dubious goodness. Add that to living with the Doctor and you're just asking for trouble.

Ianto leans back, abandoning his pie, trying to ease up a little. He knows he's being harsh, but he feels that someone must be the voice of reason here, if no one else is going to say 'hey, you can't just pick up lost little girls and drop them on the doorsteps of well-intentioned but dangerous men without maybe informing them about other options or calling child services or anything but doing what you did'.

"I just don't think it's safe," he tries, which is a slightly different argument that maybe the TARDIS will find more palatable. "The Doctor attracts danger when he's standing still. Anything bad in this city will inevitably involve him. Adults can choose to stand by him, but children... that isn't fair."