I reckon that so many people voted for Tom and Camilla that the producers were worried. It was obvious that T & C would have to be in the dance off, even if they got the most viwer's votes. It was also obvious that, in that case, the judges would have to vote them off. So the Beeb decided that, rather than risk yet another Strictly Fiasco, they'd let all three go though. The show's timing (or rather lack of it) shows that it wasn't expected.
I just wish that the producers and judges would wake up and accept that the show is either (a) a viewers' choice or (b) a dance competition.
If the Judges want a proper dance competition then they should just bring back "Come Dancing" and let the viewing figures slip back down to single figures. If it's a genuine viewer's vote then the viewers should be able to decide, not a stroppy frustrated wannabe-dancer, a sex-starved former hot gossip granny, dance school pensioner and Bruno (the only decent one of the lot).