I think the difference is that while the Golden Rule deals with actions (equatable to "hard skills"), the Platinum Rule deals with behaviors (equatable to "soft skills"). The latter does not say "render unto others the actions that they most desire", but rather "given that you are going to perform an action, perform that action in the way that best matches the way the other person is most comfortable with". It is not about the ethics of an action, but rather, how to behave in ways that are most receivable by other people.