BV,
As PAS I'm well past the window for any FRI to retain me so I wasn't speaking from a personal perspective - I had my FRI many years ago which I enjoyed spending but wasn't really a critical part of my decision to stay in, that was more down to my enjoyment of the job. I was seeing things from the perspective of someone much younger, without the prospect of advancing to Level 35 PA pay as a Flt Lt and with the rather questionable benefits of an AFPS 15 pension at whatever age it will be paid out.
If there is little point in serving until age 55 given the pension gap & the intent is only to do 5 more years to amortise the FRI then frankly it makes more sense to jump earlier & take whatever lump sum you're entitled to when you go instead of the FRI with the expectation that your 'lack of loyalty' will be rewarded through additional seniority over the coming years.