Not only does the Doctor not save Kid Davros, he also commits a worse sin—dangling the possibility of radical optimism and ingenuity in front of the kid and then just leaving with the promise unfulfilled. The Doctor seems to be almost in the process of turning Kid Davros into one of his companions, until he realizes who this is, and he offers the notion that even if you only have a one-in-a-thousand chance of survival, that one chance is all you need. It’s almost crueler to introduce hope and then take it away, than never to offer it in the first place.