Super twist. He's not even the enemy. The entire DLC is you helping him return so he can help you kill Akatosh. Without their patron god, the Empire crumbles and opens the door for the Aldmeri Dominion to take full control of Tamriel, setting up the events of TES6.
How dare you! You just want things to get worse and worse, dont you?

I'd honestly want a sort of Elder Scrolls renaissance after all this misfortune in the past games.