For the review manager, it means that the review summary needs to contain all the information the manager has taken into account when coming to a decision. If there were discussions out of band, they need to be summarized. If there were discussions _on the list_ that haven't made their way into formal reviews, they need to be summarized.
A review manager should act like an impartial judge through the process,
not like the library’s lawyer.
To me, this reveals an implicit culture, not a formalized process. If the RM was given clear steps, responsibilities and instructions, these disagreements on diverse interpretations of "what the RM is supposed to do" would not be happening. To me, Peter's email is precious information, and should be somehow translated into guidelines, process, docs, templates ... for the RM so it can be agreed on and preserved :) Best wishes and kitties, Arno