He’s not a threat to the moon of Kenshi anymore or has any ambitions to be a future one. Is a trip to the Ashlands necessary in a Kenshi play through? I guess the only reasonable reason is a trip for the collectible Meitou Weapons.
In terms of doing what's good really the only people who need to be shut down are the aggressive nation states and the slavery industry. Past that you need to feed everybody (which the game doesn't really handle so you have to presume it happens if you bring stability and freedom and managed democracy).
A lot of the bosses aren't really doing any harm to anybody. Or they stay highly localised. Maybe the cannibals and the fogmen also need sorting out though. Just because it's gross.
After the Dune Eaters roamed The Great Dessert, I had to take the two cannibal leaders down. After that the cannibal spawns in The Great Dessert come to an end.
The Great Dessert
I'm thinking some kind of epic sundae?
The sundae never sets on the Great Dessert Empire.