Ma'am, I believe the holster he is referring to is the pocket holster that has a hole through which one can reach the trigger and fire the gun. The holster is not a "holster," as such, but a rectangular holder for the pistol that keeps it from "printing," that is, from showing the outline of the pistol through the pants pocket. What one does is pull the pistol and "holster," together, out of the pocket, reaches through the hole in the holster and pulls the trigger.
One definition of "AOW" is a firearm that has been made so that it does not look like a firearm. BATF has ruled on these types of pocket holsters, and they are AOWs and they DO have to be registered.
And don't worry, I don't take your sarcasm and condescension personally. Suffice it to say that, from this limited exchange, it seems I know quite a bit more about guns and gun regulations than you. I'm happy to have had the chance to educate you.
To add to my earlier post, it's very possible that the gentleman has a later model of DeSantis wallet holster, which requires the gun to be removed from the holster to be fired. Such a set-up is completely legal and not subject to the NFA. DeSantis no longer makes the original wallet holster that has a hole through which one can reach the trigger, but they are still fairly common.