I don't think we should be trusting anything Mottom says, about the corruption of fate or the fear she holds or anything. She's one of the Demiurges - she wasn't thrust into a war where she unwittingly conquered the gods, she chose to wage bloody conflict and rule one seventh of the multiverse. She's resisted every attempt at rebellion or assassination presumably attempted on her so far. And she's not afraid to antagonize any other Demiurge than Jagganoth, considering she exploded Gog-Agog's face. If she was sick of eternal life and glorious rule then she would stop eating the peaches and die. She's not. She loves every moment of this. And she's the Demiurge embodying Gluttony. If this was Jadis of Sloth speaking then I might feel differently, but Gluttony doesn't tire. She's never going to be full and satisfied with what she has. She'll just keep consuming all things she can. And this is part of a plan to secure her own power, somehow or another.