Do I think this is the "official story", No. Of course not. But in terms of actual national security threats; not just the ISIS/Russia/ect propaganda-- a contractor bringing home terabytes of data is worrying. This is actually a huge threat to NatSec. This isn't whistleblowing this isn't treason; it's incompetence. Whether this is where the shadowbrokers kit came from or this is a patsy, this is irresponsible.
The information this guy had is almost certainly leaked. Whether he had a "convenient" penchant for bringing his work home and became the fall guy, or whether his home was compromised, or whether he outright sold them, its obvious this was dumb.
I don't love the NSA/FBI ect. But they are gonna do what they do so they might as well do it securely.