> What is the distinction between the two that changes the justification?
That one is a form of bias whereas the other is the opposite of bias: you don't want elements of an ongoing inquest to be released independently because they don't provide a complete picture of the investigative results, and thus provide a biased outlook on the event.
> I see those things as part of each other, as in institutional secrecy is bred from ongoing inquests in perpetuity.
NTSB inquests have never been "ongoing in perpetuity". They provide thorough and extensive public reports.
Their entire purpose is to minimise future risk and they're very good at that. The point of discretion until all the facts are in (what you insultingly call "institutional secrecy") is that until as much as possible is known, there may be a major piece missing from the data which changes everything.
