I’m not a pipe smoker, but I smoke ‘smooth pipe tobacco’ in my cigarettes, because pipe tobacco is exempt from the PACT act (and also is taxed MUCH lower than cigarette tobacco) This works because there is no legal definition of what ‘pipe tobacco’ actually is. If the manufacturer says it’s for pipe use, it’s pipe tobacco. Now, I remember reading somewhere that pipe smokers sometimes sprinkle snuff on their pipe tobacco to enjoy the flavors while smoking. So, considering nasal snuff can be used as a pipe tobacco, (as a flavoring sprinkle) what’s to stop manufacturers from packaging and selling snuff as pipe tobacco? I can’t imagine that it would draw much attention from the Feds, because snuff is such a niche thing as it is, and was probably never intended to be caught in the PACT act anyway. Have I had a moment of genius, or have I just snuffed too much Wilson’s SP? 
The anti-tobacco fanatics have been hard at work, trying to close the “loopholes” you mention, long before you thought of it. They’d like to prevent all interstate tobacco sales, or tax them into non-existence, if possible. They discovered the pipe tobacco discrepancy early on, as many vendors of roll-your-own cigarette tobacco simply changed their packaging to read “pipe tobacco.”
…but they haven’t stopped them from selling it in this way, which is my point. Will they close the loophole? Maybe, but they haven’t yet.
I can’t imagine manufacturers putting their reputations on the line over it. You could order pipe tobacco and grind it up though. Edit: just found your other thread. haha
It’s all been said before, and it get’s to political.