If that's what Julianne was actually going for, I don't think it was a workable strategy. When voters have supposedly rushed to the defense of a couple, it's because they thought the judges (or a judge) was being especially harsh or rude to a couple. Julianne's score was exactly the same as that of the other two judges on a night when all the scores were exactly the same (has that ever happened before?). Even her comment wasn't about the "star" but about Mark's tendency to showboat and was made without the kind of tone that most people would be likely to find mean-spirited. Or at least that enough people would be likely to find mean-spirited enough to heap votes upon Mark and Christina, unless they would have anyway.
It wouldn't overly surprise me if Mark and Christina got a relatively early boot, however. This season is quite competitive. Of those who are left, even the dancers with lower scores have points in their favor--they're entertaining or they're obviously trying and happy to be there or they're not nearly as bad as the worst dancers of other seasons or a combination of all three. At some point, someone is going to go home earlier than they might have in a different season. Christina probably doesn't have the fan base some other "stars" do, and with the scores relatively close together at this point, that may make a difference.
Actually, I also think Mark was probably lucky that it was Julianne judging that dance in place of Len too. I could easily imagine Len objecting to all that "nonsense" at the beginning and the amount of time they spent out of hold. He might have knocked off more points for that than Julianne did.