Since 1999 Examiners have been independent of schools, though they may work for, or even own a school. The CAA used to send all Examiners a reminder 6 weeks prior to the authorisation expiry date to prompt Examiners to complete the revalidation in time. Recently, I have spoken to a number of Examiners who have not received any notification at all. The Examiner nevertheless has a personal responsibility to ensure that his licence, ratings and relevant authorities are valid when conducting a test.
I suspect that if the Examiner completes his revalidation, the CAA will have its money, and the process can continue, there is no "safety reason" for not doing so, it is purely an administrative matter. If that is not the case, then the Examiner should return the candidate's fee and reimburse the expenses incurred.