are primarily paper-pushers (analysts). And no, they're not supposed to write books and blogs during the time they're working in those agencies, at least not anything having to do with those agencies.
There was a rule when I was there that any publications had to be approved before publication. I wasn't writing then, though. No, they can't be recalled to service if they quit working there. They can be prosecuted, though, if they reveal any classified information.
When I left the USAF, following my term of enlistment, I was working in the NSA building. One of the things attached to my discharge was a travel restriction that lasted several years, which prohibited me from traveling to several countries, and required me to notify the agency of any travel outside of the US, 90 days in advance. I didn't take any trips like that, though, so I never had to bother.
I can say that I worked in the NSA building. I cannot discuss what I did inside that building. Still, almost 50 years later. I signed agreements about that. So I don't. I can say that I was a Russian linguist in the USAF, and an analyst. That's on my DD Form 214. I cannot say anything about what I actually did while serving in the USAF, though, with those skills. Still, almost 50 years later.
Even though what I did wasn't all that interesting, it's still classified.
I'm pretty much a rules-follower about such things, despite the fact that what I was doing was boring and of no interest to anyone, really.
I sometimes write about the NSA, but anything I write can be found in the Wikipedia page on that agency, frankly, or on other unclassified websites.
As for my screen name, it derives from a business I used to have of selling mineral specimens to collectors all over the world. I closed that business down in 2007, but kept the screen name.