The whole point of this type of abuse stemming from authority is to make the abused discredited, typically by recruiting people into one's defense (and, in fact, Alison cites a specific instance where she was recruited into defending). What would be unusual in a case of systemic abuse would be to find no one who stepped up to defend the abuser who had no direct knowledge of the abuse.

Their opinion is clearly irrelevant to the question of whether abuse occurred, and that they would offer such an irrelevant opinion is neutral evidence at best.

Also re authorities, you're talking about people on the Tor project, and most systemic abusers are pretty careful to not provide a clear chain of evidence. So you're asking someone to go to an authority they likely specifically distrust to blow up their relationship with their community likely for no gain, since there will almost certainly not be a successful prosecution. I'm sure you can see how this might not be an appealing option.