OAP
The state doesn't profit per se, because the money for the AFPS divi pot is granted each year by prerogative instrument (compared to other unfunded schemes, funded by statutory instrument.).
So it's always 'there' somewhere to be spent, except it gets shunted from some other g'ment pot to the AFPS one. So, I can see an abstract justification in applying a cut off in the sense that the trustees can't justify being funneled tens of millions extra which, demonstrably, won't be paid to anyone and will just sit there on the AFPS books creating an accounting drag. It may as well stay in the central pot. By contrast, a modern defined contribution pension can simply have any unclaimed funds parked in cash ready for decumulation.
What I do have an issue with, is the nasty, mean spirited and subtle change to referring to claims being 'out of time'. Why the sinister implication - if there was not an intention to rely on that then why use it? And if there isn't a contingency fund ready to dish out all the unclaimed money to the hundreds of ex SP who all of a sudden respond to the awareness campaign (!) to have them come forward to claim their pension then why not and why is there no campaign? And if/when the Normal Pension Age creeps up to 70, then what?
So, you'd like to think that someone, somewhere would wake up to the fact that there are lots of ex SP out there, possibly completely ignorant about their entitlement, and most likely the ones most likely to benefit from a thousand or so extra finest quids each year. The trustees don't have to track them down or even publicise the matter, but just because you don't have to do something doesn't mean you shouldn't. As you imply.. what military covenant?
Forpen doesn't have the mandate so who is left? At this time of year too..?