It doesn't matter. The show is a money-maker for Sci-Fi, and that
is what determines whether a show stays on the air; ratings are incidental to that because the determine the ad prices. The difference in what they charge for say a Mac commercial at 2.1 is probably no different than what they charge at 1.8. It also has good demos, brings some long-desired acclaim to a channel with very little going for it and sells well on DVD, iTunes and will do well in syndication.