However, having not read it makes it tough to ask intelligent questions.
But here it goes anyway :)
Assuming I'm following the proposed theory correctly. Have you found any information outside of lower Egypt that lends support?
The reason I ask is that it would make sense to me to also preserve "information" regarding the vaults and their subsequent re-opening and use "off site" so to speak. If the expected devastation was to be so vast as to require building monumental vaults wouldn't you at least put a "spare key" in a likely safe spot?