Basically, regarding the participation of non-members in committee proceedings, there's a quote in the book that says usually when a committee proceeds to sit in camera, non-members will leave by themselves as a courtesy, but the committee can, by a motion, allow non-members or anybody else to stay. The intent of the motion, I guess—and I don't want to speak for Mr. Bezan—is to make sure that for every occasion, if a non-member is present in camera, unanimity will need be sought and obtained for that member to stay.
On November 3rd, 2016. See this statement in context.