Confirmed by whom? Which source? I went to the entry about "Robert Anton Wilson" and I didn't see any quotes to references that he is linked to the CIA. It is also not mentioned on his Wikipedia page AFAICT.

That R. Gordon Wasson was part of the US government doesn't surprise me. That fellow thoroughly grilled John Marco Allegro with all kind of fallacies which are thoroughly debunked in Irvin's "The Holy Mushroom".