It's not Petrana's motivation that Simon doubts, only the logic she'd presented to him, with which he can't quite bring himself to agree. Her pragmatism is at least a better way of looking at the situation than Kit's dogged and inexplicable optimism, as far as he's concerned, but it still leaves Benedict as the Inquisition's problem, the templars' in particular.

He feels ever so slightly as if he's been tricked here, but he can't articulate why and opts not to try. If Kit wants to negotiate, Simon will meet him halfway. There's no harm in it, when anything they agree on is going to remain hypothetical anyway. Neither of them has any power over the situation one way or another.

"Listen, it's obvious that you feel awfully strongly about this. You must have seen something in him that nobody else has, but for the life of me I don't know why you're so keen to take it at face value. You don't strike me as a gullible man."