The seat pins should have been moved to 'Safe for Maintenance' position and signed/countersigned by the armourers prior to being towed into the hangar after the previous flight. Although the Seat Pan Pin had been fitted by the pilot, the armourer concerned is required to check the correct fitment of that plus the MDC Firing Handle and the MDC Firing Unit Pins (all fitted by the pilot) in each cockpit.
4 days later when towed out, they should have been placed 'Safe for Parking,' again requiring a check of all pins as well as removing the Main Gun, Rocket Initiator and Manual Separation Firing Unit Pins. What happened during the time in the shed the BOI should know from aircraft paperwork.
Is that how it is done now? There were no differences between maintenance and parking during my service, all 5 pins would be in UK wise, or 4 RAFG wise, (jag) though I cannot remember if the 5th pin was fitted for maintenance, the pins were just checked by whoever was operating as a Liney, be it a Flem or single trade, they were trained to check / inspect the seats.
The armourers didn't do them on AF/BF or turn rounds unless they to were operating as a Liney and as such would cover as one person would do, the whole jet. From checking the engines, airframe, electrics, NAVWASS, through to refuelling, oils and gasses such as seat oxy etc, the armourers simply rearmed / rerolled them and cleaned the guns or seat removal and fit.