A cargo shift would only explain the tailscrape, not the rotation in the weeds.
It sounds to me that it may be related to the Sing Air 747 incident in Auckland. Incorrectly entered V speeds and thrust.. too low for the weight which caused an early rotation and tailscrape.
Reports of three separate strikes on the runway would tend to confirm that.
Ironically one of the contributing factors in AKL was that the Captain had just converted from the Airbus, so the lower settings didn't set off any alarm bells.