No, this man had a profound genuine experience.
> 1956, of drugs
part?
Doesn't that mean basically that experience can't be "psychedelic", unless it is a consequence "of drugs" (by this definition)?
If you try to dig into the "letter", it also specifically names drug-induced experiences "psychedelic".
Wiktionary does not mention any kind of "expanded consciousness" except the "belief of ... power of weeds", which refers to "psychedelic" in the meaning of "induced by drugs".