This is great advice, and combine it with talking to him. My son was into Tate, and then Rogan, and a few others throughout his years. He would tell me about something they said and I would tear it down with logic and empathy, and then explain the right mindset from which to view whatever the given subject was. Indoctrination requires isolation, so keep an open dialogue, and an open mind, and talk them down from the ledge.