That does seem obvious, doesn’t it? In which case it becomes just another tool for a far-reaching, zero tolerance government.
Arguably, there is less risk of improper firearm handling from a smoker than a drinker; imagine the furor if action were taken regarding the latter.
By federal standards, alcohol is legal. Hell, prescription pain medication is legal when prescribed, and there’s an enormous epidemic of illegal pain medication abuse in this country, yet none of those addicts would be lying on a 4473.