You are right, the nuclear scenario has been getting almost no media attention (maybe they are worried about mass panic). That simple fact has concerned me quite a bit as well.
The first thing I thought about in regards to the helicopter threat was an air-blast situation with one of the supposed suitcase nukes. Seems like that would be a god way for them to maneuver said nuke into an optimal place before detonation.
I still fully believe there are at least a few nukes out there and I think Adnan el Shukrijumah is tied to the plan in some way, shape, or form.
The helicopter would also be a good platform for B/C dispersal. All that wind below the rotors. Mixmaster.