What comes straight to mind is embezzling the ill-gotten money, but is this even safe? My other neighbor knows I am into Bitcoin and he learned from me, I guess that's how this other neighbor knew, I told him to go meet the next neighbor but he said he is not ready to teach.
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?
a. He is using it to cover his tracks or at least the money that he is receiving in his dealings.
b. He wants to be a investors and hide his money.
I guess you are in a lose-lose situation, you can't say no to him if he approach you and wanted to learn about bitcoin. Because maybe he will take it negatively and maybe come after you. If you teach him, then it might bothered you later as you are the one who lead him to launder his money thru bitcoin and stay under the radar from the government or the authorities.