Every termination of a salary position includes language that bars people from talking about their departures.
Company I work for just cleared 22 positions. They were salary and got severance packages and these same agreements.
This is SOP for every company that lets people go.
It is not the termination, but the alleged payoff that could end up being problematic. Was the payoff after the accusation, or was it part of the termination that led to the accusation?