That's what it's always been. Even if there were a moral framework that's provably true, people could still choose to act against it (assuming some kind of free

That's what it's always been. Even if there were a moral framework that's provably true, people could still choose to act against it (assuming some kind of free will, even if it's compatibilist). What do you do when someone hears all your arguments and says "so what"? The same thing you have to do in a universe where meaning/morality is not intrinsic: convince those you can, and force those you can't, if it's important to you.