They really are the ultimate foils though are they not?
The Gorosei and the Admirals both represent the ultimate soldiers of the WG, they both stand at the top of the WG hierarchy, the difference being the Gorosei completely sold their humanity to Satan while the Admirals still have their humanity, buried under WG propaganda but it is still there. When you view them this way, the Admirals really have to fight the Gorosei, they are perfect foils to one another.