For all the 'dead' this topic might be, I have to weigh in on it one more time, and it'll probably die and get buried somewhere in Subsim land, but I actually put my programming cap on today and played a little game of Let's Pretend. If I were Ubisoft in this case, and there's no easy way to disable having a stabilized deck gun, I think we're looking at it from the wrong angle. Given the current behavior of the deck gun and watching a few skirmishes in multiplayer, I'm not entirely sure that deck guns are "stabilized" in the first place; I think it seems a lot more likely that the firing points were just treated as free-floating points from their inception; in a sense, an imaginary/invisible pseudo-model completely detached from the sub itself.
On the other side of the coin is the argument that there's no easy way to disable it because Ubi spent a whole ton of time and resources in getting it just right, then decided their work was so perfect that they declared it must be hardcoded, and no-one was to ever disable it! Possible, but not plausible, I say.
All in all, it really kinda seems to me like the issue isn't removing an existing stabilizing feature, but rather adding a destabilizing feature in... After looking at the New Real Deck Gun files in S3D, I'm sorta following the idea behind it, but I'll have to let it sink in for a bit and mull it over. I don't necessarily think it's a lost cause, but it's certainly not a weekend project, either.