Maybe they'll be hoping that a Wing Commander or MACR won't be focusing too heavily on the pension benefits; that they'll be basking in the autumnal glow of 5 more years top notch salary and (potentially) a further decent CARE accrual rate - especially if they joined late. It does create a potential sticky wicket though - do you open up a new career stream; one that accepts the sacrifice of further AFPS accrual for the extra years? Who might the idea appeal to? How about someone who was made the subject of a pension sharing order in his/her 40s and who might look on the new potential career extension as the ideal opportunity to regenerate a fresh, independently worthwhile retirement fund.
But if accrual is uncapped for '15; surely, there must be grounds for a crewroom (at least!) judicial review if there is a compulsion on that person who has to remain on '75 and who is discriminated against by being unable to grow those benefits. AFPS Trustee/HMRC guidance prevents Added Years bolt ons after aged 46 or worthwhile additional contributions, so what to do? Maybe simply allow scheme transfer if it proves to be in the scheme member's interests - we always assume that movement won't be - but it might be.