It is not authoritarian to take aggressive war off the table. In a modern constitutional democracy, the people can only express their will in the bounds of the law. Killing Israeli or Palestinian civilians is obviously illegal under any constitution imaginable (including the current constitutions of Israel and Palestine). So, a fully democratic government who represents the will of its people could nevertheless be bound not to attack it's neighbor.

Also, I'm not seriously advocating for this. It's a fantasy that has no chance whatsoever of happening. But it is probably the only sort of thing that could bring a quick end to this conflict given the current parties in power.

I don't follow at all. Killing civilians in a war is not illegal under any constitution I'm aware of; only killing your own citizens is, generally. Israel already has a fully democratic government, so I'm not sure what you're proposing to do here. And while Gaza is obviously not democratic, if someone did set up a fully democratic government there, and the people voted for Hamas as their leaders again with their stated aim of attacking Israel, then nothing changes. Maybe I'm missing something in your proposal idea, but history shows that people in democratic societies can and will vote for warmongering leaders.

Your original comment said that leaders committed to peace should "be installed". That doesn't sound democratic in the least. And here you say that "it is not authoritarian to take aggressive war off the table". When you're talking about outside forces forcibly taking over these places governments and "installing" new leaders, that's the definition of authoritarianism. Israel's leaders were already democratically elected, and obviously they're not peaceniks, and if Netanyahu suddenly died of a stroke, I think it's naive to think the Israelis would now vote for peaceniks. And I think it's very unlikely that Gazans, given a new vote, would choose peaceful leaders either, though I could be wrong of course.