You misunderstand, I'm not saying your values necessarily have to be 'rational' in some deep sense. I'm just saying that in order to figure out what your values might be, how they are related to each other, and what that means, you have to use something like rationality. I would also posit that in order to figure out what rocks are, how they are related to each other, and what that means, you have to use something like rationality. That obviously doesn't mean that values or rocks are 'rational', but it might mean you can notice interesting things about them you wouldn't have otherwise.