Ok, so this is strange.
After I loaded up one of the older saves in which he was in "god mode", I saw that he was laying dead on the ground. I had multiple save files in which he was invulnerable and every time when I loaded in he was dead.
Everything he dug before was actually gone, but he was laying on the ground.
The Up-My-Ass-Colony Cycle 37.sav - Seven Duplicates are still alive, including Devon.
The Up-My-Ass-Colony Cycle 36.sav - Two Duplicates are still alive, though Devon is dead.
The Up-My-Ass-Colony Cycle 35.sav - Everyone is dead, Colony is lost.
And yes, I called my Colony "The Up-My-Ass-Colony"... I am very creative with names.