I don't know. It just seems that there are an awful lot of books out there that DON'T make it to the EX-jw private collectors. Just a guess on my part, I certainly don't have any inside information. It would seem to fit their M.O. of suppressing any unfavorable information due to "new light" though. LOL!
I would think the 1934 Yearbook would be high on their list of literature to "buy back" if the opportunity presents itself.
Sorry for making such a definitive statement on what really amounts to a slightly paranoid guess... blame it on my doom and gloom-everyone-is-out-to-get-us upbringing.