Three dollars and some change

You're not reading too much into the books at all. Dumbledore can't drop the habits of a lifetime; he's still all about "the greater good". Meaning that he'll throw away a goodly number of people to achieve it.

He was definitely willing to throw away Snape's life -- he and Voldemort knew what Snape did not, that if Snape disarmed/defeated him, the Elder Wand, which Voldie coveted, became Snape's. Except Draco disarmed Dumbles first, which Dumbledore hadn't planned on happening.