Optimist?
Pom Pax, either you are one of them or a real optimist. No system upgrade takes 4 to 5 days. What they do is basically let the passengers believe that they still can fly until the date mentioned. The date gets updated based on the information OX receives from DCA. Initially it was the 14th, then it moved to 31st, now it says 21st. If DCA decides to postpone the release of the findings, you will see the message being updated.
Do you really think they would post a message saying: "as we are under investigation by the DCA and the chances are high that our AOC is going to be revoked soon, you can only make bookings until 21st July".