Zod made it clear his goal was to kill the entire human race. What possible reason does Superman have to believe that Zod would follow him if he ran away? What's to stop Zod from just turning around and start slaughtering civilians until Superman comes back to stop him?
And Zod brought the fight back to Metropolis. Not Superman.
Sorry, but I will never view "Run away from the violent monster who just vowed to commit genocide" as the appropriate action of a hero.