Menos Grande have been known to absorb more and more Hollows and evolve to a higher level of power. Aaroniero went further, his Abilities allowed him to absorb Hollows and also maintain any unique abilities gained from them and the likeness of the souls involved. Gillian-class Menos do not need to absorb more Hollows to prevent themselves from reverting to a lower state and thus the lack of need for absorbing the Hollows shows that his continued absorption is a matter of Greed and desire for their abilities rather than needing them.