You need to decide what line of thinking are you using
1. Fuji and Ryo can't complete high caliber missions because they aren't strong enough to complete since their powers to IQ battle
2 Fuji and Ryo can't complete high caliber missions because it goes against their characters and plot wise.
If you pick up the option 2, keep in mind that's not the point of the "1 Admiral = Multiples Gorosei" debate. We're clearly talking if 1 Admiral is strong enough to perform in a high caliber mission as multiple Gorosei