You’re demonstrating a utilitarian sense of ethics.

And even more specifically, act utilitarian ethics. This incredibly narrow focus on the immediate effects of actions on the individual level which they treat as the only possible way of looking at things with absolutely zero examination.

I'd describe myself as a rule utilitarian, and from that perspective, the rule of "Don't support genocide, period" has a much stronger track record historically than, "Don't support genocide, unless you have a really good reason."

There is not one single time in all of human history that a stubborn refusal to support genocide has produced undesirable results. There are countless cases of people committing genocide because they see it as a "lesser evil" or "the only viable option." "If we don't kill them, they'll kill us, so we have no choice, this is the lesser evil." But not only are liberals utterly ignorant about moral philosophy, they're also ignorant about history, or they refuse to learn from it.

Modern American liberals are the ideological inheritors of the people who took the more "progressive" approach to indigenous people of subjugating and forcibly assimilating them, killing any who resisted, as opposed to the people who simply wanted to exterminate them all (who now live on through republicans). It's no wonder that they struggle to understand any perspective more progressive than "humane" genocide.