I think you're dead wrong on this one. Bruce contemplating outright killing The Joker completely nullifies the one aspect that Nolan worked so hard to establish in Begins - that Batman is no executioner.
I don't see how he's wrong. The story is about Bruce getting lost inside the monster. He's more Batman, less Bruce Wayne. Meaning he's at risk of losing his humanity. I expect him to just contemplate killing The Joker, like in DKR. Joker is definitely going to force Batman to kill him. But of course, Batman won't do it.