My own pet theory is that the person who is closest to catching on or has the least "buy in" to the concept of the show is the one who gets canned. Daniel already seemed to have an idea that something was up and Elli was definitely suspicious, last week I thought that they were both clueless though.
I think your theory makes the most sense. If these candidates honestly came into this show thinking this guy was for real, then if they start to figure out something is wrong, then their task performance will show it, so their team boss picks them to go before L Paul Todd to get eliminated.
I wonder what will happen if someone on the winning team gets suspicious and ends up staying an extra week though. Although, I have to admit these guys seem pretty clueless. I think the casting folks really put them through an extensive screening process, not only to find people somewhat telegenic, but pretty dumb as well.
I'm really curious who the mystery boss is.