The problem is that you're trying to make sense of stupidity. Why is a Glock frame a firearm, but the barrel of a Ruger 22/45 is considered the firearm? Why does putting a forward grip on a pistol magically change it into an AOW? It's not limited to firearms, did you know that allowing a non US citizen to LOOK through a night vision device is illegal?
The point is, a lot of the rules are arbitrary and senseless. You have a few choices though...
1. Follow the rules
2. Ignore the rules
3. Ask them to change the rules <- Thats where I was going with this thread.
Has it been done? Is it worth the risk? I guess the answer is Yes and No.