Michael, spokesperson for Koch Media, just explained on the cinefacts board that they opted for Dolby Digital 2.0 for
The Punisher because they noticed that there are problems with the surround sound with the DTS HD Master audio. This happend when the mediabook was already produced.
You can think of this what you want, but his statement sounds pretty honest. You can read it in full length here (he also comments on the quality of the unrated scenes and the artwork, the latter receiving a lot of negative response):
THE PUNISHER (1989) - Dolph Lundgren (Koch Media) - Seite 25