If you really support Rand you won't keep pushing this. If you make it a really bitter fight between the two, the supporters of the two candidates will do anything but support the candidate that pulls ahead and that WILL assure a Christy victory.
I don't think it'll work. If Rand lost and Cruz won, I'd vote Cruz no matter what happened in the primary. I'd suspect people who vote Cruz would do the same for Rand.
Obviously this theory of mine discounts a lot a lot of posters on RPF, who are extremists and don't represent the average potential Rand voter.