SCD final and X Factor final have always been on the same night right? The weekend before Christmas week. This is because the X Factor winner aims to be Christmas Number One and because SCD are in competition with the X Factor.They also had the SCD final followed by the Christmas special the following weekend. This year, accoridng to Wikipedia there was only ever going to be two acts in the X Factor final (although oddly this sentence has now been removed). It makes sense though and was the reason behind the "double eviction" the other week.
Now stick with me on this one. There are 5 weeks left before the final in each show. X Factor has 7 contestants left and SCD 8. That means that X Factor would have their 2 finalists and SCD would have their 3. Therefore the Tarbuck early exit has had no effect at all??! Unless SCD was planning a double eviction which they've now scrapped. No need then for a "twist" exciting or not?
Thoughts?

The Strictly final is planned for 23rd December, a bit later than usual. So there are 6 weeks left before the final. So either they've decided to mov the final, or the twist is still out there.

I can't see them working "live" the day before Christmas Eve. The Xmas Special last year was filmed on the Monday the 19th Dec and transmitted on the 24th with an Audience vote.
Perhaps the 12 week run as advertised has always included a Special filmed in advance for transmission on the 23rd?