It's conceivable that Cruz is laying the groundwork for a presidential run in order to position himself in case Rand does not run for whatever reason (family issues, health issues, whatever), or to position himself for being a potential VP pick. I'm not really going to be too critical of Cruz unless/until he actually declares he is running or unless/until he starts portraying Rand negatively.
Well I hope it isn't your son or daughter that a President Cruz sends to Iran in order to defend Israel then.