One issue is the definition of “nuclear weapons capability.” There is a vast difference between having the capability to produce nuclear weapons and actually doing so.
It is not irrational to argue that Iran already possesses “nuclear weapons capability” and has had it for some years. The Iranians possess the uranium and the ability to enrich it and may be nearing a plutonium reprocessing capability. They certainly have the scientific and technical expertise to produce a weapon given the time and a political decision to do so.
The resolution also calls for “the full and sustained suspension of all uranium enrichment-related and reprocessing activities.” In other words, it would seem to have Iran give up most if not all of its nuclear programs, peaceful and otherwise.
There is a legitimate dispute as to whether Iran has the right under the nonproliferation treaty (NPT) to have full nuclear fuel cycle capability. But this dispute must be decided by negotiation, not a resolution.
Iran is an NPT signatory but has not fully complied with International Atomic Energy Agency (IAEA) inspection and other procedures. A negotiated agreement wherein Iran retains a civilian nuclear program, as it is entitled to under the NPT with IAEA inspections and safeguards, would resolve this dispute and ease fears of an Iranian nuclear weapons program.
But the resolution has another problem beyond the capability issues. It asserts that containment is not an acceptable outcome. President Obama has already made this clear, so why object to the resolution?
The short answer is that the document adds nothing on this point and, more importantly, could be taken to authorize the use of force if Iran gets a nuclear weapon. The resolution blocks a containment strategy and endorses US military action regardless of any other circumstances.