Extremely interesting that you have referenced this exact information, as I was about to post it myself just before you did, but decided not to, as it was late. Thank you.
There is actually much more on the Heinlein connection to witchcraft and the occult, if one desires to make the connections.
As the Patterson biography of RAH was done in two books, several years apart, and due to my own research, I found it significant that Wm Patterson himself died the day (or the day after) the second book was published.
the Patterson biography of RAH was done in two books
Have both volumes.