The regulatory arrangements for ensuring that this aircraft was both airworthy and serviceable rests with the Civlian regulator, whether devolved or no. The regulatory arrangements for ensuring the military regulations are implemented and complied with by ETPS (or any other unit) rests with the MAA.
When Regulation is done on the cheap people die. When regulation is compromised by protecting VSO reputations people die. At least the AAIB can and will produce an objectively neutral report when published. Does this SI do likewise?
Self Regulation Does Not Work, and in Aviation It Kills!