Some of them do tend to let things go and live like they are in a frat house.
I had to laugh about the bedroom starting to look a bit cleaner, especially photos of his university days. Oh, my, longing for those days gone by.
If he's on a cleaning binge, he's wanting to start anew w/something different. Many of them do this. They don't want any reminders of what they once had and yes, they want "change". They think that if things change, especially where they are living, that things will be better. He will continue to change a lot of things and experiment in other areas, but the bottom line is this...yes, the new will be exciting, but the euphoria of the new item will grow old and he'll have to seek something else to give him that "euphoria high" for a bit.
It's typical script for some of them. I wouldn't worry about it too much...from the sound of it, the house needed to be cleaned up since he turned it into a pigsty for quite a while. Who knows, maybe he'll find the magic rock that will bring him back to earth. LOL!
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.