: Scientology founder L. Ron Hubbard, whose exploits at that
: time were closely intertwined with those of Parsons, is
: only mentioned by commenters to that article.

Hubbard was Naval Intelligence and may have been assigned to Parsons due to his job at JPL (Jet Propulsion Lab) vis a vis his occult life. At any rate Hubbard expressed interest in Parsons' occult practices, and they became friends. Hubbard eventually ran off with Parsons' wife and his yacht.
Sometime later Hubbard began writing Dianetics, borrowing extensively from Crowley's doctrine of Thelema.