As is somewhat evidenced by who was put in command of that fleet, I recall that Kris mentioned in one of the UF forums that the Manticore Star Navy and any references to it were his additions, to basically act as third-party fleets allied to the Freespacers, but wouldn't receive any actual screen-time or serious roles. If I remember right, Gryph wasn't overly fond of David Weber, but I could be mistaken.