The can regulate it because they are regulating what you vape not necessarily whats in the liquid.If it Isn't Marketed/Advertised as an e-Cigarette, or Part of an e-Cigarette, or Included in a "Kit" that contains an e-Cigarette or and e-liquid that Contains Nicotine, I don't see how the FDA can Regulate a Non-Nicotine Product.
There's the deadly nicotine. Then there's the other stuff in the juice that contains all sorts of little
nastie's. As simple as this sounds this is how they can,will and,are going to do it.
Indiana has done precisely this.
Bring me up to speed,where did your definition come from and in what context.
Regards
mike