This girl is stupid, like you know by experience the danger and how wild he is yet letting one of their (seems like) worst represent go meddle him, and just praying to god that (seemingly) bad spirited girl not triggering him.
I don't know the term, but in term of stalker games, it's like letting that one known retarded member of your group going to the chimera's forest, it's good if that person died there or come back as is, but if that person trigger one/a pack of chimera and leading it back to the camp then that is just dumb of the other group members to not stop that person, knowing how likely he will mess up if not supervised.
Also, do they not have history lesson talking about the past heroes or the one person who defeat the demon lord to give them the rough power scale that he hold in the world. Half of an entire country is destroyed and nobody feared the guy, even the intellectual?