Just a thought

whatever you do do not present him the faq from this site

why you ask

because he will take it as nonsense seeing as we are procannabis and will probably not listen to it

I have made the same mistake and I got nowhere

Your probably never gonna get through to him, some people are just too damn stubborn, but hell take a shot in the dark and try to get him to see your point of view maybe one day he will see the light and finally understand that what you are doing is practically harmless