Withers: After waking up from centuries of sleep in a sarcophagus, he quickly figures out how to monetize his unique skill sets. Then when those skills are no longer needed he changes career to party planner.
I do quite enjoy this feeling I get that deep down he's very entertained to be around the party. Like in a tsundere way he likes us. Although Tsundere Withers isn't a word combo I ever imagined typing down, but him planning a reunion party 6 months after the fact just for shits and giggles is awfully out of character for what you'd expect out of an ancient, cold ex-deity, so one can only think he does like us a little bit, I guess mummies can't blush.