I think Maynard just used a story about an alien visitation/abduction as a way to express an experience that is unexplainable any other way than a metaphor. He speaks through this character, who is frantic and rambling, after he ingested ecstasy and DMT. "They chose me?!" When you are comboing these drugs, you are choosing yourself to have an insane experience, Maynard just wants to warn us that yes drugs can be a beneficial thing but you don't want to overdo it and shit the bed.