Yes it is a HQAC camp and is run by HQAC
OC RIAT is indeed a CFAV, but is a CFAV on HQAC books. not a Squadron, not a Wing or Region, but HQAC, just like the OC Eng and OC Ops roles - these are Volunteer roles in thier own right, no longer secondary duties.
Back in the day 20+ years ago it was a WExO run camp, back when they were WAdOs, B&G WExO ran the camp as the Camp Commandant, for B&G, Dorset&Wilts, Thames Valley and No1 Welsh.
the camp soon grew as RIAT realised what the Cadets could do for the show, and so demand for Cadet “man power” was increased so did the camp.
the camp grew to a Region event, but still run buy the then WExO - now on the second B&G WExO.
Having become so big, HQAC got involved and sent down TG2 for a few days each year until it was decided HQAC would take on the role. A Wg Cdr was appointed
this brought about many changes, no less so formalised roles within the structure of the Staff.
That Wg Cdr ran the camp for several years, until they stood down as part of “retiring” from the Corps.
the replacement as @wdimagineer2b indicates is “one of us” - or at least once was.
He is ex RAF, and later joined as a VRT, became a successful OC, while holding Wing roles and what is now recognised as “OC Eng” for RIAT.
When his predecessor (the first HQAC appointed OC RIAT) stepped down, this individual was the obvious choice and so became OC RIAT and was promoted to Wg Cdr and with it the HQAC appointed role “full time” as a CFAV.
12-18 months later the OC Eng and OC Ops roles were also created as primary roles for a CFAV and not secondary duties. Both of these individuals are ex-Cadets who attended RIAT in the earliest of days was it was ~30 Cadets and only the Senior Cadets attended. they have since become VRTs, ran Squadrons as well as having Wing roles, and since been promoted to Sqn Ldr as part of the “full time”/primary role as OC Eng/OC Ops.
Although OC RIAT is every bit a Volunteer as we see on Squadrons, he has his “office” at HQAC, walks the corridors there and is regularly seen checking in on FB at that location for another meeting.
Being a HQAC appointed role he knows the HQAC Staff well and as such when putting in a request, or raising a problem regarding RIAT it attention as he’s talking to the likes of Dawn’s team and others they influence.