Welcome and well done with the book. It seems to have got rather heated immediately in here.
I find the evidence you have identified for seed storage quite compelling. It brings these structures into line with other ancient stepped structures such as the Ziggurats of the Middle East. However, I think the idea of a SV type recovery vault may be stretching the idea a little far.
The other step structures are considered seed/grain storage centers for the living. They collect in the good times and re-distributed to the hungry during the droughts. As such how do you distinguish between day to day storage and the RVT proposal. There would surely be a need for many many storage centers in the ancient world. There should be many times the number of standard storage vats to RVs. Have you identified lots of the former and shown a reasonable way to distinguish between them from the latter?
I would also like to know what precautions the storage vaults made to protect against the water that was found beneath the Giza plateau and at Saqqara?
The flooding was a biannual event so it was probably a catastrophe of the ilk you are describing, one that would presume the need for good storage facilities. What makes you think they could really predict global catastrophes and thru what mechanic?