DV,
I wasn't party to any of the work that underpinned this mod, but some interesting observations on platform out-of-service dates might go some way to explain how it came to be embodied on Tornado but not Hawk. The mod was introduced in the mid-2000s, so would have been staffed in the early 2000s, when Tornado OSD was still 2025. I don't know what the Hawk T1 OSD was meant to be back in the early 2000s, but I do know that it has been put back (I think as a combination of MFTS shenanigans, provision of international defence training, and undoubtedly with a nod towards RAFAT preservation) and now falls after Tornado OSD, which has been brought forward to 2019.
The following is all my postulation: perhaps the cost-benefit part of the ALARP calculation back in the early 2000s decided that the "long" remaining life of Tornado made it worthwhile to fit the mod, while there was insufficient benefit gained from the "short" remaining life of Hawk T1. And by the early 2010s, when the OSDs were changed, the Hawk still had insufficient life remaining to make embodiment worthwhile.
At any rate, that would be a procedurally-correct and justfiable reason for having 2 different mod states of seat. It's almost certain to be the case that, in reality, the Tornado and Hawk cap sponsors, PTs and operators were operating in totally separate 'pillars of excellence' and didn't notice what each other was doing...