It is a great idea, but I think it is the structure itself that won't allow you to do that. You can upgrade two different characters in university simultaneously, but you cannot upgrade two chapters of the same character at the same time. The same is for armory, you can upgrade raiders and planes (with the second slot), but you cannot upgrade raiders and mortars at the same time.
Correct me if I'm wrong but implementing your idea would change the whole approach to upgrades.
I agree with no angels about citizens, no citizens should be needed for university upgrades like for library or armory, but not for XP.
XP points are given only upon buildings upgrade, only exception is library. Units upgrades do not provide XP and so the univeristy does...