In which case whichever club official decided upon this policy is complicit in facilitating an illegal public transport activity. The insurer's position is nihil ad rem .
Face it - there are sufficient properly qualified flight instructors around to meet any conceivable club recency requirement. Whether the club is prepared to provide sufficient properly qualified people to support its self-imposed requirements is clearly another matter with clear commercial considerations.
In other words, do it properly or don't do it at all!