Moral relativism doesn't do away with evaluation. It's a system for arbitrating who has standing to judge which aspects of a particular culture. Those who are members of a culture do not have their standing to evaluate their own culture reduced, nor is the prerogative of any individual, anywhere, to speak to the impacts of any culture outside its boundaries reduced. All it says is that outsiders have no businesses judging the internal relations of foreign cultures.
I don't believe in moral relativism because this is illogical. That is a con job based on philosophy and bad science. If you look at marriage, for example, married men and women have the longest life expectancy. This higher level of longevity connects marriage to natural selection, since natural selection is not based on picking the worse but on picking the optimized.
Bad science using science magic tricks came up with relativism since that was the result philosophy wanted, putting the cart before the horse. Even with the data of longevity, the con is still being exploited by mutant science.
What moral relativism does is create more jobs and more pretend experts. If eating dirt is as good as eating cereal, since it is all relative, we can sell dirt along side cereal. This creates experts and jobs.
Another logical standard one can apply to help see through the illusions of relative morality, is to compare the social costs for each relative behavior choice. Natural does not have a social safety net, which is why it tries to pick the optimized. The safety net allows the con to appear real. But if we eliminate it, hypothetically (compare costs) the cheapest is natural.
For example, say we con people to believe that dirt and cereal are relative foods. As long as we have a lot of medical resources to assist those who eat the dirt so they become par with those who eat the cereal, we can say these are relative, since the final result appears the same. The social cost is the magic trick. There is a lot of money to be made assisting relative, so the con continues.
The same trick is used for moral relativism. The social cost is used to offset the real differences so we can con people to believe it is relative. The experiment I would do is remove all the social safety net and resources connected to social relativism and let nature take its course.