> not an incident that should meet with curious blameless fact finding
The NTSB "fact finding" is intentionally and necessarily blameless, because if it becomes a prosecutorial investigation then you lose cooperation of everyone involved. If you lose that cooperation, you can't work out what caused an accident, and so the same accidents keeps recurring.
The entire point of the NTSB is to find what caused the accident, and that's not going to be "Sarah was tired that day", "Frank was distracted by his kid's academic struggles", etc. That might be relevant (a common action by budget carriers use to be frequent schedule changes for line pilots, so that they had "sufficient" sleep by the law but were being forced to work through their circadian low, etc - stopping that took multiple crashes where the NTSB said "this is the cause"), but it isn't going to be the cause here. Afaict it takes multiple people to install the plug, all of whom failed to do or check the bolts, Boeing has a lot of cross checks, none of them caught this, Alaska did an acceptance flight and had performed maintenance, but did not catch this, etc.
Firing the mechanics involved doesn't tell you why they messed up, it doesn't tell you how this got through checks, it doesn't do anything other than provide retribution. It doesn't even do anything to the people who presumably created the environment that allowed this to happen.
So instead of trying to get retribution, we try to discover what made it possible for this to happen, so we can stop the same thing happening again in future. That is how flying got as safe as it is today.
People who cause accidents due to criminal behavior, or corporations that cause the accidents due to criminal behavior, can be charged or sued, but saying "I want people punished so lets sabotage the accident investigation, and inhibit our ability to prevent them in future" is counter productive.