100% - I would have taken a simple "This isn't working out for us. We appreciate your efforts. Today will be your last day." over all this.

For insult on injury, they declined severance "as we do not offer severance for performance-related termination", after acknowledging that it had been shown that my manager had done nothing to actually assess my performance in the PIP (I suppose their claim will be that the performance issues led to the PIP).