The reason he had such a bad habit of forgiving people and giving them second chances when he really shouldn't was twofold. One, there were too few wizards in the world and less were being born on either side of the divide each passing year, and two, if he forgave them no matter how bad they were then maybe they would find it within themselves to forgive him one day.

The people who'd been raised on stories of sweetness and light in recent generations had seemingly forgotten that Good didn't necessarily mean "Nice". Oh, he tried to be, tried so hard, but when it came down to it, he was nowhere near as nice as he pretended to be.

He couldn't afford to feel for these people he was saving whether they wanted it or not. He couldn't afford to feel for the ones he was leading to their doom in order to save the rest.

Led to doom was a bit strong. He never actually made the choices for them. He may have nudged and guided and strongly hinted on occasion, but they made the final choice on their own without any outside compulsions aside from those associated with the situation they were in. Sure, he could've used potions and charms to take their will away, but that was Evil, so he refrained and allowed those whose deaths would save lives the final dignity of being in possession of their own free will.

People would likely be horrified if they learned of this side of him, but sacrifices must be made if their kind were to survive beyond the three or four generations he'd calculated were left to them before he'd quietly interfered here and there.

The needs of the many outweigh the needs of the few or the one.

Good does not equal "Nice".