When I enquired about the logic since the examinee would already be a qualified pilot and even if I dropped dead there was no issue, the reply was "it's the rule".
Really? Do all integrated students take an interim (LAPL/PPL) LST before their CPL Test?
Also Examiners are required to be able to Instruct for the qualification they are testing. Sensible, I would have thought, as they are (supposed to be) part of the system that maintains standards. Not really possible for legislation to distinguish between someone who cannot instruct for the CPL because their Class 1 has expired by one day and those who have not been able to for 20 years (if ever).
Note: This only applies to Licences. Perfectly acceptable for a PPL FI/FE / CRI/CRE with only a Class 2 Medical to teach/examine for an SEP Rating for a CPL or ATPL Holder. Why? Because the Class Rating standards are the same, irrespective of which Licence they are/will be attached to.