The statement that "this area is assigned to this timezone" is not a creative decision. It's an assertion of a fact. Even if it's a false fact made up by the author, it's still an assertion of a fact.
I think you are treading on thin ice with this reasoning. By the same token I might argue that "Harry said this to Ron and Ron said that to Harry" is an assertion of the fact that Harry and Ron had a conversation. What else is a novel except a collection of false facts made up by the author?