Well Chugalug
I don't see how anybody could complain about your desire for a proper investigative authority for military incidents and accidents. So I'd support you in that.
Why not have the AAIB do it? They have a top notch reputation and expanding their remit to include the military would surely be straightforward and to the benefit of all concerned.
It remains my personal opinion, no more than that, that these guys screwed up badly by CFITing their a/c that day. I'm not doing them down. **** happens!
I'll leave you now, to do another 280 pages on why that may not be the case or why the charge laid against them should be removed and I sincerely wish you all the best in your endeavours.
Sometimes the simplest and most obvious solution turns out to be correct.