aaaand nothing there changes the legality of using marijuana in a legal state.  
"Are you an unlawful user of, or addicted to, marijuana or any depressant, stimulant, narcotic drug, or any other controlled substance? 
Warning:  The use or possession of marijuana remains unlawful under Federal law regardless of whether it has been legalized or 
decriminalized for medicinal or recreational purposes in the state where you reside
See the way it works is this: are you unlawful user: no, addicted? impossible, and the "use or possession" does not prohibit you from a gun, only a felony conviction will.  
Just because you are righteous, does not mean you can add your own judgements to the law, even if you are a TSA agent.  Knowledge is freedom.
-a US Army veteran, 7th Infantry