Are you trying to say that any kind of discussion around ethics or values is pointless because it's possible for people to disagree?
I think it's much better to discuss actual policies rather than to question the point of even being able to have discussions around what people think would make for a better world.
I think they are pointing out that if the first principles are completely different, everything that follows after will be different also. What is good/bad determines what policies should be pursued, and those actual real-world police’s may be as different as night and day.
I think it's much better to discuss actual policies rather than to question the point of even being able to have discussions around what people think would make for a better world.