What will you do if something like this is happening around you? Why would a drug dealer want to learn Bitcoin if not for a safer haven for running the business?
My mind isn't settled as I keep thinking different things, what is on your mind readers?
My short answer: NO!
You should not teach him about something like that or even get involved with him as you said he is onto drug dealings. He will probably do illegal things. I understand you know a lot about bitcoin/crypto stuff but are you a teacher? Just directly reject him and say you are busy.
And if he is so eager to learn about bitcoin, there are more qualified persons (google,YouTube, WhitePapers) to teach him. You can get tons of knowledge from them. There is even bitcoin talk.
So buddy my opinion just ignore him. Cause maybe not today not tomorrow but in the future he may use crypto for running his illegal business. Hope it clears the confusions.