The Doctor would probably warn against holding or any physical contact with the baby, paradoxes and all.
Though in this case, I think it's okay. If something were to happen, it would have happened by now. Plus they had a weird thing happen where future children showed up from different futures. With their parents knowing that should already alter the future, but they're still here.
What I mean to say is that I think it's okay. He shouldn't have anything to worry about.