Just as the other members said, it is not a DM benefit - neither published nor unpublished. If there is a separate F queue, then DMs can queue up there. Otherwise, DMs should stay in the J queue.

Years ago when there were only a F/J queue and a Y queue, the gate staff will sometimes lead F passengers and DMs traveling in J to the head of the F/J queue, but that was only "by invitation only".