Have put this on the other thread but will re-post it here 
I have a theory about Emma Bunton grin She announced she was pregnant fairly soon after the show finished and I worked out she would have known she was pregnant by the time of the final therefore would not have wanted to do the showdance with all the big lifts. So, I think it was fixed so that she would be in the dance-off and the judges put her out so that it wasn't an issue and she didn't have to pull out and announce her pregnancy early.