They haven't officially taken the position that they are destructive devices, but it hinges on the gun specifically having a "sporting purpose" which other shotguns, such as the jackhammer and street sweeper do not meet, and are therefore destructive devices, even though they have non-NFA barrel and overall lengths. It is indeed a scary proposal for all of these guns, whether or not they were purchased before or after their status changes (IF IT DOES OFFICIALY CHANGE, and it could)
Imagine a hypothetical nightmare: That it does change for the worse and, not being an FFL, you don't keep up with the ATF newsletter reporting this change. Imagine going to court having used your home defense cruiser in self defense, rather than your 40" break barrel duck gun. Imagine a vile anti-gun prosecutor that has done his homework and states in court that you shot an intruder with a "unregistered destructive device". The black ugly gun argument now has an ugly legal definition to go with it!
It's probably not as bad as the hypothetical worst case, but we all know how slippery slopes work and i doubt they produced this, or any other rulings, for "shits and giggles"
