Never heard that one...show me in writing.
In all my dealings with nitrous in Fl its just a Guns said...the legality pertains to what type of nitrous it is. Do not get caught with medical grade nitrous. You must use nitrous+, which has sulfer dioxide to prevent substance abuse. The bottle must be clearly marked for nitrous + or the cops can atleast take you inand arrest you under suspicion. Which has happened in the past. Penalties for having and distibuting medical grade nitrous are very stiff...along the lines of drug trafficking.

So...be sure you only use nitorus+ from a good vendor. Be sure your bottles have the appropriate labels, and dont drive like a jackass...and youll be ok.