There seems to be a misconception that the MAA is solely about Air Safety - It is not, it is the Regulator in the same way the CAA is the national regulatory representative of EASA. In that way it assures airworthiness and audits; application of regulation, management of Risk To Life (RtL) and the individual Duty Holders.
Making it a civilian or civilian led organisation would potentially fall back into the previous traps of malaise that befell certain IPTs in the past.
Military Flight Safety is not the issue, inter-service bickering at the senior levels and individual failings have been.
I do like the suggestion though, that the DG should be at the twilight of his career and therefore not be seeking further promotion.