I'm not apprivied of staff conversations, but I entirely agree with holding at DEFCON 5. Iran is not a nuclear threat, at least not in the immediate or imminent sense. Long term? Yes. But the alert level isn't for long term threats but immediate ones.
Iran is nowhere near a immediate nuclear threat. Not anymore at least. Begining of this mess maybe when we knew a lot less about the state of their nuclear program. But now? Nope.
They are now just a terrorist infested bed of hate and evil with it's only card gone in the wind. For now... Tho... Long term future? We're screwed if not handled or left to fester.