The GOP Establishment doesn't think Ted Cruz is going to win or change anything, so -- as much as they dislike him -- they don't fear him all that much. I think they fear Trump more. Win or lose Trump is going to shake things up, maybe disastrously so.
Cruz is a politician they don't like, but someone who's recognizably part of the club with similar qualities and abilities to other politicians. Trump is a real unpredictable wild card, and that's what they fear most.
Editorial establishment eyewash.