jeanne i think you have them mixed up. souma is the logical one since he only strives to better his kingdom right now while the empress is the emotional one from what you said about her thinking that all kingdoms must assist each other to fight against the demon.
she also said that they must get back van from souma's kingdom due to dignity. i know that dignity is pretty important for a kingdom but there are times that they must be cruel and enforce the declaration. the non emotional way to do it would have been if they didn't assist them to take it back. i don't remember if the declaration said that if they don't sign it then the empire won't be liable to attacks but what i do remember is that the use of force to take land is not allowed. which is what the principality tried to do. they broke the declaration hence should get punished.
she didn't look at it in the way where she could get more control over the other kingdoms(logical) but the route of dignity(emotional) where she wants to try to keep things the way they are. thus she is the emotional one.
@codydub03 i totally agree. i mean she legit said that our boy throws away those who can't be used and usually people who can throw away non useful things are the logical ones.