The confabulation was picked up by people who, for various reasons, wanted to believe it was true. But there was no truth, there was just people looking to control others, and people willing to be controlled.
As the occultist Agliè explicitly champions, "in its loftiest sense syncretism is the acknowledgment that a single Tradition runs through and nurtures all religion, all learning, all philosophy". He asserts that "true esotericism does not fear contradiction".
None of what was published could falsify the syncretic paranoia-therefore whatever existed was the cult, since no tradition could be excluded.
That was the genius bit of the book, IMVHO.