Some good points there Scattergun. To answer your question - its pure speculation but maybe the photographer was making a net profit if he was shooting the scene for a movie (I doubt a James Bond movie!) or a TV programme or an advert where there would be profit, he might make enough for several Europe trips! Maybe his project was simply get a series of surreal shots and once that was done had no more need for the pictures.
Personally if I had wanted a shot of the room I could have taken them down, but I didn't want to move them out of respect for all the work that obviously went into it. I've got loads of respect for anyone else that decided not to move them out of respect for a fellow photographer.
Maybe the guy that set it up isn't the photographer, but just printed and framed them to get the exhibition set up for another purpose. Personally I think it would be good fun if someone takes them down and sets them up in another derp!