This is not the action of an agency which accepts and owns its mistakes and wants to do better. Instead, it is the action of an agency which refuses to accept it has done anything wrong, and seeks to bury the evidence of its misbehaviour. Its a sign that the SIS has no intention of changing its practices. That they are perpetual recidivists who cannot ever be reformed. Which means that if we want our democracy to be safe from them, we have to destroy them: defund them, disband them, reduce them to a rump protective security / security clearance agency.
Meanwhile, I guess the lesson for the future is that you should always take the SIS to trial. Because any "settlement" from them will simply be an exercise in bad faith.