Although Jeanny said that to Jack, she was not entirely against the idea of forming a coalition with these guilds with whom they had worked together during the war. John also thought it was a good idea. They didn't need any solid purposes like doing a joint epic quest to band together like the previous coalition. Simply some mutual exchange of information was good, as well as a pact to help each other when one of them needed it.
Hearing that, Jack said that he fully supported the idea and would let them have full authority over how to manage this cooperation with the other guilds. Jeanny and John gave him a hard stare as a result.