I agree, the NTSB has operated in such a way that Conflicts of Interest are almost impossible. I have lost several good friends to aircraft crashes, all but 1 of them died as a result of "pilot error."
Recently the NTSB faulted both the crew and ATC in crash that killed a former coworker of mine. In my opinion and experience, if they have to make the "hard calls" they do. I just can't see the NTSB getting into coverups and mistruths. So sorry for your loss.
RadialGal