A likely explanation for the damage is that the hull ruptured (maybe
as a result of corrosion induced cracking) and the sudden admission of
high-pressure air to the inside of the fairing blew it off.

Have been looking closely at a high-resolution image of the hole over
on PPrune. Something about the damage to the wing root fairing attach
points doesn't look right to me.
The forward and aft upper half of the frame around the fairing is
either still attached, or shows damage to the attach structure. The
lower half- especially on the aft side- show what appear to be intact
attach lugs and screw holes.
Not sure what sort of fasteners would be used here, but irrespective,
I would have expected to see damage all round the outside edge of the
fairing. Is there some mechanism that might cause a small section of
the fairing (remaining after the rest of it has been blown off) to
detach in such a way as to leave the screw holes and lugs intact?

If the fairing is also attached to the hull in a few places in the
centre (by brackets- perhaps to prevent vibration in the airflow), and
had not been secured properly on its bottom half, then the reverse may
have occurred- that is, the fairing became detached, twisted upwards
and the load on an internal attach bracket ruptured the hull, setting
off the explosive decompression.

I'd be surprised if those screws were broken in tension- but I
suppose it's possible....

Coop