In other words we shouldn't rule out the possibility this aircraft may have had no issues with loading at all, but may have had an unexpected instability in roll from the moment it got airborne.
This is very interesting. As I understand it the 747 is positively stable when normally configured. It's been described in this thread as having benign handling, and D.P. Davies certainly enjoyed it, although he was describing the B741, whereas the B744 has a different wing.
Apart from an abnormally rear CG, what would cause uncontrollable lateral instability in a B744?
I'm reminded of video of a TU-154 Dutch rolling. I'd always thought Dutch roll was characteristic of swept wing aircraft at speed and altitude; I remember Brian Trubshaw (or Roland Beamont) describing switching off the yaw damper in the cruise in a VC10 and the phugoid soon taking it to nearly 90% of bank.
Would a B744 Dutch roll to this extent in T/O configuration if for some reason its yaw dampers (if it has them) were inactive? I've been PAX many times on B744 and watched it slowly and gently wag its wings in the cruise; something I've never seen on A346, for example.