Fair warning: I don't know enough about mathematics to say if this is the case here. I hear this all the time, but this is actually a real phenomenon that happ

Fair warning: I don't know enough about mathematics to say if this is the case here. I hear this all the time, but this is actually a real phenomenon that happens when well-known senior figures are rightfully cautious about over-citing their own work and/or are just so familiar with their own work that they don't include much of it in their literature review. For everybody else in the field, it's obvious that the work of famous person X should make up a substantial chunk of the lit review and be explicit about how the new work builds on X's prior literally paradigm shifting work. You can do a bad job at writing about your own past work for a given audience for so many different reasons, and many senior academics do all the time, making their work literally indistinguishable from that of graduate students --- hence the rejection.