Yes, Pickering is an insider’s insider. But if he first declined to testify, and as of Wednesday he wants to, that would suggest that he heard something yesterday that he wants to squelch real hard. That runs counter to the party line put out today that there is nothing to see here.
That internal review that Hillary assigned Pickering and Mullens to conduct seems to be under some review itself, although the administration has tried to discount that by saying that all such internal reviews are part of the action.
There is something there that is very important.
The Inspector General of the State Department is investigating the ARB because there were a number of people who wanted to testify, but weren't invited.
Indeed, some of the principals weren't interviewed at all. Among others, Hillary and Hicks.
Further, there was evidently no stenographer and no recording of any of the interviews. Nor were witnesses allowed to review a transcript of their testimony (there being none). Accordingly, the Board was free to edit the testimony in a fashion favorable to their conclusion (or just make it up).
At this point, I would imagine the Committee would defer to the IG rather than have Pickering testify -- as it is not the ARB that is under investigation, but the event itself. Pickering's desire to testify is likely self-serving.