Re: "no self respecting spook would be caught using Microsoft Windows to do their spying"
Given that almost 90% of all desktops these days are still under Redmond's rule, I don't see how you can realistically avoid using Windows all the time.
Now, a spook should know better than to use a Windows machine for work, I'd think, but the real problem here stems from the very probable fact that, spook or no, management will be using Windows and management wants their time sheets, planning, expense reports etc done on time. I haven't heard of a lot of Linux versions of the products that handle that, so you'll be most likely using Windows for all that stuff.
Compound that with the natural human tendency to be lazy - especially in the geek arena - and you have a contractor bringing work from a secure environment to an environment where security is an afterthought because who wants National Security-level hassle on one's private network ? To go on Youtube ? Nah, no need.
Add a zest of overconfidence (I got a super strong password on my wifi router) and willful ignorance (hey, it's me, nobody's interested in what I'm doing anyway) and here we are today, learning that Russia can read stuff on your PC via an anti-virus program.
The basic mistake here is a contractor leaving the NSA building with confidential documents and no oversight. I work regularly at various client sites (banks, insurance companies, ...) as a contractor ; do you have any idea how many places I can slip a USB key in the slot and copy files onto it ? Zero. I have complete access to server files, sometimes I even have admin access to the server itself, but USB ? Forget it.
Why is this even possible at a site that is practically the brain of National Security ?
I don't get it.