It is possible that Jonah suffers Post-Traumatic Stress Disorder , an anxiety disorder that makes the infected wish to prove himself. Especially if the said person is known as a hero of some kind. As in Jonah's case, his time in the military may have traumatized him. His many decorations and general's chevrons hint that his followers see him as a hero. At some point, he may have been dishonored, wich causes him to prove his hero's reputation valid. Jonah likely sees his presence and control over Shangai as a way to recover his fame and respect.