Why Guttenberg must resign

From here on, every time Guttenberg speaks in public, no matter on what topic, the first question he'll be asked will be: "Why do you think a man who forged his PhD should be minister of defense?"

He's the head of the universities of the forces now. The army can't take him seriously anymore, but he is supreme commander. If he doesn't resign, this will overshadow all of his actions and make any leadership impossible. He must resign.