Re: What's implausible ...
"Cease being surprised. It's been stated often enough that it was a contractor."
Why would the contractors be given more access and privileges than the regular personnel? Can they just download all the goodies into their infected laptop full of warez and carry it out of the place just like that?
Snowden was a contractor. The docudrama carrying his name may or may not have been accurate in depicting his work conditions, but it certainly didn't seem easy to carry documents or *anything* out of the place. I'd hazard a guess that NSA has reviewed their security afterwards and are even more strict these days.