Mortwake decides you do, in fact, appreciate his handiwork. Kearnen nearly gets mad enough to walk out on you, but sticks around long enough to take out the Defias kingpin while Mortwake has the Defias minions distracted with his ludicrous necromancy. He then accidentally pacifies Kearnen by taking his army off to take over the jungles to the south.
And with that, everything is cleaned up.