Wait a second.
The rules of AFPS75 state that an individual must complete at least 2 years’ reckonable service in the substantive rank in order to receive a full pension for that rank; if they complete at least 12 months’ reckonable service in the substantive rank, there will be a proportionate increase in the pension award based on the rates payable for each of the two ranks.
Unfortunately, as our Staff Sergeant did not complete 12 months’ reckonable service in the substantive rank, his AFPS75 pension award will be based on that of a Sergeant for the full 19 years.
That's got to be wrong. AFPS75 is based on final salary so surely if this man completes 2 years in rank (even after transfer to AFPS15) then the ENTIRE 19/20ths will be paid at SSgt rate and not, as is suggested here, as a Sgt.