Lieutenant or CaptainEdit
Starfleet payed little attention to the USS Vitality in the 24th century, as there was little need to. The ship's mission was to repair warp tears in space; so they appointed a mere Lieutenant as Captain of the ship.
Although, technically, Tru was now ranked Captain, he was continued to be referred to as Lieutenant by higher ups that had known him in the past. In a way, it was hard for other people to accept him as a Captain, since his previous ranking and experiences were the latter.
Because his experience in the field ranked him as only a Lieutenant, in any other position outside his mission to repair tears, he was reinstated to his rank of Lieutenant.