User blog comment:Xilinoc/Ch. 621 - THE DARK CURTAIN/@comment-7805464-20150326160740/@comment-5693502-20150326163732

The Soul King's power is engraved on their bones so would that account for anything ?

If the Royal Guards were to change sides (for some convoluted reason) it would give the Shinigami down below something to really fight against (bankai time !).