Well, he's had thoughts that opened up the possibility of how the walls are moving here. One idea was that they might be mechanical - someone mentioned that - but he's offered alternatives based on in-the-moment observations, namely a supernatural/magical sort of option. I know it kind of requires a suspension of disbelief, but when you run out of possibilities you kind of have to look outside the box

Have they ever moved in a way that seemed almost purposeful way? I mean the doorknob biting you, even if not a wall, kind of fits that.