Well, his daughter is going to college and then doing whatever she wants to do, so that's not much of an issue. His wife probably moved into the Crypt Dungeon with him or he just takes days off to visit her. His mobs probably won't attempt to stop him again since he's "The One Who Came Back." But overall yeah, that was not wrapped up very cleanly.
I dont think he ditched them? He decided to work here as the dungeon boss, and I guess he moved his family here? SInce he did say he can be near his son, if he works at castle balck.
But ya, felt like a huge axe fell on the plot line. There's enough plotline for 2 whole arcs, fighting against the rest of the GameMaster AIs and final arc fighting against the Devs for more rights to Mobs. Not to mention the so many unanswered questions like where the fuck is redgon etc...