It obviously doesn't guarantee squat because all Iran has to do is give the IAEA the finger and do whatever they want to do, just as they have previously.
Usual false attribution. Even you admit that Iran hasn't produced weapons grade material. If they really want nukes, they'll have to produce some, and the IAEA is there to tell us if they make the attempt.
It always comes back around to alleged "nuclear weapons related activities" from a decade ago, doesn't it? activities that never involved nuclear materials at all, right?
How does that affect the the IAEA's mandate to supervise the production & handling of nuclear materials under the NPT? Why is that so important, other than to obtain information to discredit Iran & block the verifiably legal aspects of their program?
How can the IAEA claim to want a deal when what they want to find is a way to prevent one?
As I've offered many times, none of it amounts to very small hill of beans in the absence of weapons grade material. It's just desperate distraction from the central issue, the fundamentally sound basis of the NPT in the first place- No weapons grade material, no weapons.
I suspect that Iran has snubbed the IAEA in retaliation for dishonest dealings of the past, and in recognition that the IAEA will ultimately do what the 5+1 tells them to do. There's no point in dealing with intermediaries when there's a meeting scheduled with the Principals in the near future, anyway.