The thing is, the Doctor just had a Dalek point out his hatred, to praise his standing as a “good Dalek”, to wage pure destruction with him as the focal point of inspiration.
And then a soldier asks him to take her with him. And it must seem like Journey’s following him into battle.
He doesn’t have a “rule” against soldiers in spite of the things he has done, in complete disregard of just what he himself is capable of. But because of it.
How must she scare him, standing there, so hopeful.
A Dalek saw hatred.
What must a soldier see?
We know exactly what a soldier saw in the Doctor.
A “dark legend”, a “mighty warrior”… no wonder he turned his back on this one.
Clara Oswald in series eight episode two, “Into The Dalek”
Are you going to look that terrified when you take me out for a drink?
The Doctor: "Clara, be my pal, tell me… am I a good man?"
*40 minutes later*
Dalek: "You are a good Dalek, Doctor."