Kathryn's assertion that Billy is too sane to go back is another nod to
Catch-22, in which the paradox has to do with one's sanity dictating whether or not they can fly missions. By altering that paradox some and having Billy want to go back because of the bond he shares with the other Bravos, Fountain insists that though war is certainly something that happens on a large scale, the people involved make decisions based on their individual relationships on a much smaller scale.