Promising anything on that scale, to begin with, is ridiculous. [Especially if Katerina is a human as she's assuming.] Second, as we learned during the last trial, Katerina couldn't even save one little girl, and she couldn't prevent Undyne and her associates from fighting, nor has she proven that any of our hostages have gone free. In fact, she has delivered on none of her incentives except for reverting changes she caused herself. There's no proof she can do anything she's offering.