The grey tuniced figure on the card shot used for the vintage figure seems to indicate it's accurate.
That shot is pulled from the scene where Leia's brought before Tarkin prior to the order to destry Alderaan being given. In the shot, the trooper is in a computer console port thing that are common in several places within the Death Stars, and the trooper APPEARS to be wearing a grey tunic.
I consider him canon for that reason. This may be an Imperial Naval Trooper CO of sorts. Someone below officer level, but higher than the average DST in rank. There were also DST's in black jumpsuits I believe, ala the POTJ Imperial Officer figure. They were seen in ROTJ. Possibly they are the raw grunts of the Naval Trooper ranks, and the black tuniced chaps are a step above, and grey tuniced fellows are a step above them?
Food for t hought, as they say.
Many of the uniform types are more consistent in ANH and ESB because by the time of ROTJ Lucas did not keep a military expert on-set whereas in ANH and ESB he had the same person there to keep a uniform/rank structure to both sides that made sense and gave a strong sense of military realism.
Why this person wasn't on board in ROTJ is anyone's guess, but the lack of their being there is noticeable in the generic Imperial 4 square rank plaquards, and the noticeable uniform changes between ANH and ROTJ. There's still explainable structure to it, but it did make things pretty complicated, and the Imperial plaquard thing has always just been brushed off as an error for the most part with no attempt at "explaining it away".
Perhaps the Death Star Troopers in black jumpsuits fell prey to that same way of thinking? Though I seem to recall many in the black tunics as well though. Hell, there were even differences in Death Star Gunners too, with some only wearing the top portion of the helmet and whatnot.