Cybermen were invented as a way to cheat death. Yet in their zeal to remove pain their creators sacrificed their identities. They became emotionless drones existing only to create more cybermen. The choice Seb offers Danny is a false one. Ridding himself of the emotional consequences for his past actions as a trained killer will turn Danny back into one. The real choice is whether Danny is brave enough to face his victim. He murdered a child. It was not his intention but the boy died all the same. If he cannot take responsibility for this then the teacher will cease to exist and the soldier will prevail. Clara is mad with grief and willing to kill herself in order to join Danny. If this were a Greek tragedy or a Shakespeare play she wouldnt have lasted another five minutes. Steven Moffat tidily subverts the genre when Danny shuts her down cold and ends the call. Clara doesnt understand that she is asking Danny to bear responsibility for yet another death.