...actually this kinda does. Not so much that a good 1911 will AD, but that it violates the whole pointing a loaded gun at anything you don't want to destroy rule.... which covers all the failures causing AD's.
I believe they are referring to a gun in one's hand with finger near trigger...?
I see no way (realistically speaking) that a gun in a shoulder holster could AD anymore so than say a belt or pocket holster. I am still looking for "documented" AD's in any holster (absent human interaction to be clear)
Shoulder rigs are legal IMO for a reason (one being they are, in fact, safe).
But I totally get it that it doesn't suit everyone.