It is more than likely that due to the nature of the competition, they don't reserve all the actor/models for each challenge. As contestants are eliminated it would not really make fiscal sense to pay the same number of models they had from the start for each challenge rather than just whittling down the number. Also, I am fairly certain the actor/models likely have other gigs they do and therefore appear according to availability as well. It makes sense that although Cig had to change his plans at the last minute, it would still be a heck of a lot easier to do so seeing as they were still only at the sketching stage. Unlike Stella on Stella on Day 2. There would be a significant amount of change to be made if it was a gender swap on Day 2. They probably just asked other actress/models that were not previously reserved for the day if they were available and she was the one to step up at the last minute.
Also, Dina has been my #1 pick since Day 1. I still have issues remembering any of the other contestants the next day. Even though her makeup last week was not her usual stellar work, it was, dare I say it, memorable. I cannot remember what any of the other makeups looked like. Not even the winner. That is, until the recap before the opening credits.