I meant there are exceptions (like the Yanamoto) to the pool of people believing certain moral propositions. That Spartans taught their sons to steal does not in itself show that there is no moral law about stealing. It only shows there are differences of opinion about what that moral law is.
The being (or absoluteness?) of a law does not depend on its being known, does it? Wasn't Australia the largest island (or smallest continent) before it was discovered?
While the Spartan example does show that there are differing opinions of what moral law is, there is nothing in itself that does show a moral law either.
I think a law is quite different than a land mass.