I can only recommend this article by Ashton Gray, how investigated the whereabouts of L. Ron Hubbard and came to a very similar conclusion. And they by a totally different approach:
I concluded based on the given technical publications, that LRH worked until 7. June 1972 as a C/S and researcher for Expanded Dianetics and then suddenly and unexpected got lost and never showed up again.
Ashton investigated the whereabouts of LRH based on legal, historical and political data and this resulted into a very similar date of disappearance: 28. May 1972, 10 days earlier.
Please read this article and make up your own mind: