User blog comment:Gcheung28/Batman vs. Superman/@comment-4661256-20130201013553/@comment-2149911-20130201014239

Because Batman knows Clark for a long time, and has already prepared a plan to take him down if he ever gone rogue (in fact he probably made multiple plans and hid them in a lead cased vault). Just because Superman is like a god, doesn't mean a guarenteed victory. Batman had faced plenty of gods in his lifetime and walked away.