spannermonkey I completely agree, there really is no problem on the whole with RAF engineers or civilians as PAX in the Hawk particularly in transit.
i say that having been lucky enough as a civilian and ATPL to fly on a low level sortie through the Welsh mountains in a Hawk. The preparation for that included a RAF medical for the day, included measuring my limbs, height and weight. Likewise the briefing on the ejection seat and survival was thorough, although I do not recall being briefed on the command of the front seat from the back, perhaps intentional from the RAFs perspective.
I see no problem with engineers as PAX on transit flights, it is just practical. Likewise in respect of civilian PAX with the Red Arrows, I see no problem as the Red Arrows are there to seek publicity.
Some memorable moments for the Red Arrows in recent years was seeing Brian May of Queen fame strapping into a Red Arrows Hawk, likewise the RAF had a competition to allow nine air cadets to fly as PAX on a transit flight.