Not really a bad point. Thinking about the "Don't kill Naruto, you will regret it." talk in 309.
For all we know, the seal will break if naruto dies and the daemon fox will be free again. So preserving Narutos life isn't exactly in his best interest.

(Contradiction here, I know. In their first encounter kyuubi said "if you die, i die as well, huh. fair enough. *grant power*. But now this "you'll regret it" - i mean, how can he kyuubi haunt sasuke if he dies with naruto?) There has to be some bond between the fox and naruto beyond being imprisoned in him. Would also explain why the 4th sealed himself up with the fox for eternity. I mean, hey, his wife