Snowden is still a horrible analogy when comparing to this situation.
Snowden released classified data at great personal cost - he is now a US fugitive and will be promptly arrested if he ever tries to leave Russia.
Sarah Wynn-Williams wrote a tell-all book for which she was paid. My understanding is that she also signed the non-disparagement clause as part of her separation agreement, in order to get a substantial severance (someone correct me if I'm wrong).
I've only read parts of Careless People, and I think it's great that Wynn-Williams wrote it and exposed some details at the personal level of how nuts these folks are. But I take issue with framing her as some kind of victim ("Meta stole Sarah Wynn-Williams Voice" - give me a fucking break). Meta wouldn't be able to do shit if Wynn-Williams hadn't told them she'd keep her mouth shut for a pile of money. What did she expect would happen after she received that pile of money and then opened her mouth?
Snowden, similarly, signed a substantial non-disclosure agreement which was a condition of his employment with Booz-Allen.
Of course, considering the NDA was a condition of his employment, he was paid for his work that he could not have done had he not signed said NDA. What did he expect would happen after he received his money and then opened his mouth?
That's my whole point - I've never seen Snowden play the part of the grand victim like Wynn-Williams appears to be doing. He did his job, discovered some bad behavior, and released the information at great personal cost, a cost that he seemed willing to accept (he's obviously not happy about the consequences, but he knew what would happen). I haven't seen blog posts from him about how Booz-Allen "stole his voice".