[Davros scoffs, his shrivelled eye sockets conveying an almost pitying glance.]
That's his way of letting them down gently. So they can continue to do as he says, without questioning. Without having to think. It's what his friends say, the clever ones, the one's he trusts. All the better to make sure you don't end up hurting those you're trying to protect with your senseless stupidity. I've seen The Doctor set up entire situations, empowering his lesser companions, giving them a sense of importance and relevance... All to let them continue without knowing how dangerous they are, how if they were given the opportunity to create their own part in The Doctor's plan, they would just end up killing.
[A scowl of contempt erupts across Davros' face.]
The Doctor is the greatest chess player in the universe, and you are his pieces.