I was floored too, then realized, even though it's called a reality show, it ain't real. The producers can manipulate the show however they want. Joelle is a pain in the neck, but guess what, most people love to hate her, and are dying to see more fireworks between her and Bob, or her and Carla when she comes back, so she makes better TV. Damien and his wife are very nice, but that's it, not real exciting to watch.
I was hoping the switch was that they would ditch Joelle and put Carla in the house instead. Oh well.