Folks that are trying to go viral may be surprised when they do go viral, but, as that was their goal all along, going viral wasn’t entirely outside their control.
That was always the goal, of course.

Do something outrageous, get followers!
I think the amount of liability is based on the person, not the social media. There are at least several hundred thousands of people using social media now and I have no idea who they are or who they work for.
And you?
If the severance plan includes an NDA, then it’d be effective.

Most folks would rather take the money and run and are happy staying quiet about it.