A blurry green line for Iran?

Clive Crook rightly points out that Obama's presentation of his Iran policy in his AIPAC speech and the Goldblog interview has played out as something of a Rorschach test.  The WSJ is reassured that Obama has effectively bound himself to bomb Iran.  James Fallows, on the other hand, sees Obama's statement that "as President of the United States, I don't bluff" as a potential superbluff.

Crook tries to part the veil by focusing on the detailed case ("detailed" for a speech, anyway) Obama made that Iran's obtaining a nuclear weapon would be a severe blow not only to Israeli security but to American interests, middle east stability, and global antiproliferation.  He has thus set himself against the case, laid out by intelligence veteran Paul Pillar, that fears of an Iranian bomb are overblown and that a nuclear Iran could be effectively contained.  He has laid out the stakes in such a way that Iran's obtaining nuclear capability can be seen as nothing other than a colossal failure of his own policy

Whether Obama is committed to attack if Iran is seen to be building a bomb may be beside the point, however.  Or rather, it's not in itself news. If it's true that an American president can't be exposed to have bluffed, as Obama said, it's equally true that an American president under current political conditions can't suggest that a nuclear-armed Iran would not be such a catastrophe.  The real nub was captured, as Spencer Ackerman pointed out, is captured in a tweet by anything-for-Israel neocon Noah Pollack:

Obama policy = preventing Iran from getting nuke. Israel policy = preventing capability to build nuke. There's the rub.

Obama may be seeking wiggle room, not only for a perhaps-unlikely negotiated settlement with Iran, but for a protracted stalemate. I'd like to ask nuclear arms experts: how precise a concept is 'breakout capacity'?  Is it possible to clearly parse this statement of Obama's to Goldberg:

And we think that, without in any way being under an illusion about Iranian intentions, without in any way being naive about the nature of that regime, they are self-interested. They recognize that they are in a bad, bad place right now. It is possible for them to make a strategic calculation that, at minimum, pushes much further to the right whatever potential breakout capacity they may have, and that may turn out to be the best decision for Israel's security.

Push much further to the right whatever breakout capacity they may have. Ostensibly that means opening their enrichment facilities to full inspection and keeping enrichment below an agreed threshold. Obama argues that the route is open for Iranians to strike a deal:

The point is that for them to prove to the international community that their intentions are peaceful and that they are, in fact, not pursuing weapons is not inconsistent with what they've said. So it doesn't require them to knuckle under to us. What it does require is for them to actually show to the world that there is consistency between their actions and their statements. And that's something they should be able to do without losing face.

But could "pushing...to the right...whatever breakout capacity they may have" also mean more passively refraining from crossing subtler red lines -- continuing not show any evidence of any weaponization effort, for example,  or making incremental unilateral concessions, such as revealing a tad more to inspectors? Could the Obama administration and the Khamenei regime dance around each other indefinitely, engaging neither in rapprochement nor provocation?

As in Iraq and Afghanistan, I wonder whether Obama is once again -- prudently -- defining success down, widening the exit lanes from confrontation.

See also:
Obama maneuvers within a 'sacrosanct' commitment
The president who doesn't do sound bytes