Yes, there is a difference between a design feature and a bug ( and/or design flaw). I didn't say there wasn't. Since leaving a device open for others to manipulate without the consent of the owner doesn't seem like something a responsible engineer would do intentionally, I believe it's a bug or design flaw rather than a "feature". Unless you're friends with the Apple designers and know their intent, you have no way of knowing that leaving the IR open was by design (vs. bug). I don't need to "redefine" any terms in order to make this perfectly logical argument.
You say that my boss and I have proven that it's not a problem. Not at all! My boss and I have proven that most people probably don't even know of the existence of IR on the Macs and wouldn't know how to react when they find their volume control "mysteriously" going up/down.
You say "You indicate you don't know System Preferences..."
Nowhere in my post did I say that I don't know "System Preferences". I said that this particular system preference is difficult to find. Since my Mac gives no visual indication that there is an IR port active (such as an LED) and there is no OBVIOUS system preference that points it out, the average user won't know about it nor turn it off. Since the average user won't turn it off, it stays on. Since it stays on, it's easy for someone to have some fun with Mac users. It is not so hard to understand how this faulty arrangement may lead people who wouldn't appreciate being manipulated by someone's IR to, nonetheless, not do anything to protect themselves - because they don't know that there is a need to!