They'd have probably cleaned his room, too. It's not in as bad shape as the rest of the house obviously, but he's attached to junk like that filthy, faded baby blanket and probably other shit we're unaware of. That and he fears and obeys Barb.
As for the birthday picture, it is possible he's celebrating at the Game Place and Snyder is just off camera pissed off that his least favorite customer has hijacked the place and turned it into Chuck-E-Cheese for a day. But I still think it's a church event with dual birthday party (because that's how Elizabeth and Rocky roll). It could be a rec room they put a few game posters in in order to create a comfortable environment for kids and teens. There was a place I used to go to after school that did just that: kid and teen friendly game and movie posters everywhere (not posters for good movies though unfortunately).
