Ah, well yeah I imagine adding bones/animations is a tall order, especially since it would be for every lootable. Maybe try a different approach: just swap the models. Imagine they're both loaded well enough, would that not work, seems worth a try.
It's rather silly that I can't just close the door of an open cabinet, plus one should be able to make use of it regardless of door status. I get why you guys added the open stuff in the first place, it sure saves time while looting to just see that and skip'm.
The idea of raiding someone (which is not a thing in games I play, even MP games, but I get it) and doing that sounds fun, but would be a rare occurrence at best. Having the wherewithal to plan what that takes ahead of time is some next level trolling, the time/effort to craft open cabinets and dedicate a precious inventory slot, and so on. Thing is, if you got the models to simply swap, or whatever ended up working, you could still get that effect by simply emptying the cabinets. It would sure occur far more often regarding raids, as it would be a natural result.
Challenge for someone at TFP: try it. Try the straight model swap and see how it feels.
It would be super neat imho, in the situation you described and more. Especially in MP games where multliple people are looting. You could peer in a room and immediately tell if in has been looted yet or not, at least with the cabinets and other lootables with open versions. It would also be another time saver in SP games, making it obvious what you'd already looted, as it is now, in both situations, a looted cabinet(etc) looks the same even when it is empty.