Exactly. Hell, you can go full Godwin if you want. The Holocaust itself was justified on utilitarian grounds.

“I’m sorry, times are tough, and we just can’t afford to keep the disabled around anymore. Tough decisions must be made…”

“Those political prisoners we’ve sent to camps? Yes, it is an unfortunate violation of rights, but their ideas are so dangerous, and so harmful, that we really have no choice if we want to save society.”

“The Jews? Well you see, history is never-ending contest between racial groups, simple Darwinian evolution. And having weak genes in our country harms our ability to survive. So unfortunately, we have to do what we have to do. It’s for the greater good.”

A whole lot of SS troops went to the gallows believing they did nothing wrong.

And Hell, from a purely utilitarian perspective, I can’t even say for certain the Nazis were wrong. In theory, in a long enough timescale, could we not actually avert net suffering by committing an omni-genocide? Select one ethic group from a hat. Everybody else goes to the camps.

Sure, we kill 90% of the Earth’s population now, but think of the long term. First, with such a reduced population, global warming is stopped in its tracks. Same with most other environmental problems. But the best result? The end of racism! Can’t have racism if there’s only one racial group. So sure, we sacrifice 90% of the human population today, but in exchange we’ve eliminated all racial hatred and violence, from now until the end of time! We sacrifice 7 billion humans today, but we probably save trillions on a long enough timescale.

From a purely utilitarian perspective, we should probably select one ethic group by random and just kill everyone else. In the long term, it will reduce net human suffering.