Lelouch's "ends justify the means" attitude would make him the villain in most things. But I think the events here show that while it's a stance he wants to take, he's not so emotionally dead that he can do all this stuff with a clear conscience. That might become more obvious as the end of the first season plays out.
It's a hamfisted metaphor, but Lelouch sees his actions as Zero as analogous to his chess match. In chess, the only metric worth anything is whether an action brings you closer to trapping your opponent's king, while keeping your king safe. There's no room for emotion, and pieces ought to be sacrificed for the "greater good" of victory. His initial plan in Episode 22, on a strictly intellectual level, is just another part of that. Things spiral out of his control, but even as he tries to turn it to his advantage, he also discovers that there are sacrifices he can't make so easily. However, he isn't given a choice (
sparing Euphemia would not have ended well for anyone
Trust me, when Lelouch disposes of a piece in his life for purely selfish reasons when things aren't going according to plan, he's not very subtle about how he feels.
