No, we want them to agree to never pursue nuclear weapons.

That's not correct. They were willing to agree never to pursue nuclear weapons from jump, before the war. What the Administration wants them to agree to is to not have any domestic uranium enrichment program. They don't trust the Iranians to have domestic uranium and simply agree they won't use it for nukes.

It helps to abstract what they're saying up to the proper level: Reduce or eliminate the Iranian regime's ability to project power in the region.

That doesn't "help," because once you abstract to that level it's useless. It doesn't tell you what objectives you're actually trying to accomplish, because "reduce" can mean anything from blowing up a few planes to completely overthrowing the government through a massive ground invasion. If you set an objective that literally can't help but be met with the very first bomb strike of the first minute, then you haven't actually set an objective.

This is a bad question. We don't want them to try again.

It's not a bad question. Sure, it's a question that's uncomfortable for the Administration (and supporters of the war) to answer. But it's still a good question.

If you establish as one of the main objectives of a military operation the prevention of Iran from ever getting a nuclear weapon, and you fail to accomplish that through the military operation, then how can you regard the military operation as having already been a success?

We might not want them to try again. But if the military operation doesn't prevent them from trying again in the future, then we can't have already achieved that goal. Which is (again) the criticism that's been levied against this operation from the beginning - you can't bomb a country into not being able to make a nuclear bomb in the future.