IGh, you totally ignored the primary focus of my post. The pilots unions were excluded from the NTSB investigation because they broke the rules. I find it very hard to believe that these unions were unaware of and hadn't agreed to the non-disclosure rules up front - which means that what they did was knowing and intentional. And that is inexcusable.
It's simple - play by the rules, or be excluded. How can you find fault or accuse the NTSB of bias for following their own rules?