
You are looking at the top part of the section attachment just behind the windows.

The way the skin tore off is definitely not a clean fatigue crack, but an extreme pull on the metal, finally giving in at the weakest point namely the perforation for the first rivet row.
I can come up with only one explanation for such extreme pull, namely the momentum of a strong (and probably sudden) downward force at the tail. Something like depicted here.

This person thinks the jackscrew failed, but there are more possibilities, like a computer going mad, etc... Let that be determined by the investigators. One thing is for sure, the plane must be intact to put up such pull force. Making bomb stories less likely.
If you look at pictures towards the back of the tail section, you will see only the top half of the stabilizer compartment. If you look very good, there is only sand underneath, not the flat folded bottom half.

All this brings me to the following sequence of events.
1) The front of the stabilizer goes extremely down
2) The pull of the momentum in the roof makes it fail along the rivets of a production weakness. Starting from the top, stopping at the stronger attachments near the floor.
3) The stabilizers can't hold the pressure and sheer off.
4) The plane tumbles/soars/spirals further down and at 2.2 km before impact the floor cannot hold the tail section anymore and it rips off.
5) After that point the fire in the main section must have begun, because the tail section is clean of burn marks.
Kind regards, Vincent