I have serious misgivings about this sort of "hush money". In general, I'd prefer not to interfere in private contracts, but this one has such serious implications for everyone else. In particular, it can end up creating an information imbalance, enforced by the courts, that allows a certain group of people to remain "in the know", with everyone else unaware of what is going on. I read a while back about a law firm t…
In this specific case, the non-disparagement clause would probably be construed not to cover things like testifying before a legislative body or communicating with regulators, even if those communications were voluntary rather than subpoenaed.