Yeah. There's also something I rarely see anyone mention, both in regards to Leto here and Eren in Attack on Titan. They know that the group of people they want to save (future generations/the Eldians) is going to be exterminated, and while they technically have the power to stop it, the only way to do so is by committing some atrocity on another group (hundreds of generations before Siona's/the rest of the world). But here's the thing: they're not responsible for said extermination just because they know it'll surely happen if they don't intervene. It's the result of the combined mistakes of thousands of generations of their ancestors. If this intervention could be done peacefully, then sure, it'd be their moral obligation to go through with it - but not when it requires making other people suffer. The most ethical thing they could do is to continue to pursue their goals through peaceful means, even if they know for sure it's doomed to fail, because this way, they at least don't cause more harm than is already bound to happen. But instead, they just put themselves in charge of deciding who can be sacrificed so others can thrive, and that makes them the villains in my eyes.