Very interesting observation...Nicotine free eliquid is not covered if you walk the tight rope. Free samples would be permitted since they are not covered. But, if you become successful, they will create the data set to show your product is expected to be mixed with nicotine and crush you. Absolutely no mention of their earlier stated reasoning: a hardware unit that may be used to vaporize a nicotine containing liquid is used to vaporize a nicotine free liquid; therefore, the nicotine free liquid that is used with the tobacco free tobacco product is now a tobacco product.
There is also mention that an NFL may become a "tobacco product" based on how it is being used by the public; in other words, once somebody mentions mixing a NFL with nicotine in a public forum (like here) or social media, that NFL could then be classified as a tobacco product.