Easy Street
I've read your link. It seems to me the main point being made is that of inconsistency by, in this case, the HSE (but one could also say the CPS in England and Wales and the Procurators Fiscal in Scotland). They went after Martin-Baker in the Cunningham case, after MoD admitted guilt and liability. Yet take no action in far worse cases.
I agree with you - the HSE is non-specialist. In the Cunningham case, the judge ignored specialist evidence, as did the HSE, who were permitted to make false accusations and mislead the court.
Another point raised by the correspondent is the status of servicemen under Scots Law. That Fatal Accident Inquiries in Scotland did not take place for servicemen is not well known. People here may immediately think 'Mull of Kintyre FAI in 1996'. But that was for the RUC and MI5 officers who died. Not the RAF aircrew or Army officers. Sheriff Young made that clear in his remarks but was missed by most. The difference between Young and the Cunningham judge was that he did his job properly, and knew that he must explore MoD's actions (offences) in order to satisfy his public interest remit. The disgrace was that the Scottish Crown Office didn't follow through against MoD. Therefore, I think it unfair to say DV's campaign lacks integrity. It is MoD, HSE and parts of the judiciary who do.
The technical point you make is correct.