Bloggs:
Sounds like sour grapes to me. Unless UPS and the IPA directly, publicly criticised the NTSB, why on earth would you lock out the two major players? There must be a long history of knives/back stabbing in the USA for such a "keep your public trap shut until we issue the report" rule to be necessary...
The NTSB is a political hack government agency at the Board level, and has been for many years. (TWA 841, 1979, investigation controlled by Boeing.)
And, even at the investigator level, it is not what it once was because of "PC" hiring and lack of control.