> One of the reasons you usually don't hear about why people get fired is the employee is offered a severance package in exchange for signing a non-disparagement agreement.
Obligatory: I am not a lawyer, I am not your lawyer, and this is not legal advice.
Just FYI, nondisparagement agreements have fallen out of favor in recent years, as they're interpreted very narrowly by courts[0]. Even if your company presents you with one (which they may not), you can usually negotiate it out pretty easily.
Especially in industries or jobs in which reputation and "social capital" are highly valued, companies are tending to leave these out, because they're actually massive liabilities for both parties, and there are already enough restrictions around defamation, sharing of confidential information, etc., that it's usually not worth the risk.
I have no idea what happened in this case, but it's worth mentioning since you bring this up.
[0] As in, this blog post would almost certainly violate a standard nondisparagement agreement, even though it's relatively innocuous at first glance!