All this back and forth has not changed the bottom line for Rand: to get elected as a somewhat less interventionist President than the other Republican contenders, he feels he needs to have interventionist cover to minimize the "weak on defense" or "weak on Iran" tagging the neocons will plague him with.
So, empty gesture time: Congress votes on the Iran deal in two months, and one or both GOP-controlled houses votes it down. Obarry vetoes Congress, meaning it requires a 2/3rds vote to override him. Congress fails to override the veto, and the Iran agreement prevails. By next year, it appears that Iran is complying with all aspects of the deal, as monitored by the P5+1 and IAEA.
Meaning, since the deal is going through anyway, Rand can freely oppose it now, vote against it, and thus have cover as being "tough on Iran" through the GOP primaries. Then he can say he supports the deal later, since by then there will be evidence Iran is in compliance. Bottom line substance: The agreement prevents or greatly delays war, Iran remains independent and unmeddled with, and Rand can embrace the non-interventionist outcome as the coast becomes clear.