It's about how well the government guards their weapons.
It's also about how possession of nuclear weapons are used as very effective propaganda tool to embolden groups in many other ways. See Russia as an example of what nuclear weapons can motivate people to do despite the weapons never actually being used.
So why do you oppose a deal that will demonstrably reduce Iran's potential to breakout into weapons production? A deal that allows them an opening for much bigger and better things? A deal where the world's only superpower abandons their policy of regime change?
Crazy Mullahs? Crazy like a fox. They challenged arrogant Neocon imperialism and won. We need their govt to be there to follow the agreement. We need for it to be there forever to comply with IAEA inspections & protocols.
I figure this deal & more of the same is what they wanted all along, not nuclear weapons at all. They're plenty smart enough to follow it to the letter. We won't be doing them the way we did Iraq for the benefit of the Israelis.
More than that, they know what they're doing, that internal pressures for liberalization will mount as a result & very likely succeed. They're apparently willing to accept that.