I dunno, the logic of the GOPe is rather easy to discern. It starts with the premise that they always make the best of the situation. Thus, in seeing that Trump is likely to win they seek to win Trump over to their side. They can get to his immigration stance later but on the other stuff the perceive a guy who is Monty Hall. If they can, they would love to replace Trump with Rubio. But above all, they must destroy Cruz.
Their calculus:
Cruz gone, Donald wins, not bad.
Cruz gone, Trump gone, Rubio wins, excellent!!
Trump gone, Rubio gone, Cruz wins, sell Cruz out in the general at all costs. However you slice it, Cruz will be gone.
Right, because they could never get Cruz to support amnesty and TPP, oh wait they already did.