Yeah i think aizen know his limit and his backup from Qin wont do that much.
His best way to do only make his lost as benefit as can be, and i think Meat shield for half the series almost killed is not predicted by aizen. So i think aizen target to make hist lost as benefit as he can is done. He almost kill Meat shield for half the series with his limited source and at least leave a huge scar in his face and heart enemy. Farewell most handsome flying six general member atm