I was wrong about the 80s. Does anyone know anything about this? Supposedly, the Thai State Samgha has a regularized curriculum of learning that would ideally prevent things like this from happening, especially with the Supreme Patriarch/Samgharaja.The anatta concept has been a subject of intense debate in Thailand, dating as far back as 1939, when the 12th Supreme Patriarch of Thailand published a book arguing that Nirvana was the "true-self".
The new date would mean that the supposed author was Ven Ariyavongsagatanana III.