ASRAAMTOO, you’re quite right about the TMk1 seat set up. The same system - which is the responsibility of MBA - is fitted to all Hawks built over the years, with the exception of the 200 series which only have the rear seat position, the front having been used for the avionics bay behind the radar, and as a single seat aircraft have no need for it.
It is not however just a simple modification. With command ejection selected, the rear seat instructor is able to operate their seat, which in turn sequences and subsequently operates the front seat. With a modified system selected to front command, the front seat occupant would pull their handle after which the system would pause the front seat while the rear seat is then signalled and operated, after which the front seat would then fire, thus preserving the need for the rear seat to leave the aircraft first. The pause in front seat sequencing and the need to prove its operation would make the qualification and certification of what would be a major modification a more challenging process than simply adding a couple of pipes and wires.
While the path to RAFAT OSD, previously 2030, is unclear after the latest announcements, a modification would be unlikely to be in place before the retirement of the rest of the TMk1 fleet, thus leaving the same passenger concerns in place for continued FAC training on 100 Sqn.
It is worth noting that the T45 Goshawk (Douglas/McDD/Boeing responsibility) does have a system selectable from either cockpit. It is however fitted with the Mk14 NACES seat, not the Mk10B used in the Hawk.