[ventus45]

An interesting find indeed, and well done Annette.

I have a feeling this may prove the ditch rather than the dive.

The "dive" scenerio.
Considering that the toilet is behind it, a sudden deceleration during a dive impact, would certainly break the toilet from it's mountings, it moves forwards, fracturing the panel, and releasing it. But then, it, and everything else forward of it, and everything behind the toilet to the rear of the aircraft, all concertiner foreward. It, and everything else frangible, would be pulverised, as the impact sequence continued, in only a fraction of a second.
If we assume a crash velocity of around 400 knots virtually vertically, that is about 670 feet per second. The whole of the aircraft, from nose radome to tailcone would enter the water in less than one third of one second.
The dynamics of that, are violent in the extreme.
In short, I can not see any way that this panel could survive such a violent impact sequence in the condition that we see it.

On the other hand:-

The "ditch" scenario.
Considering that the toilet is behind it, a significant deceleration (say around 10 "g" horizonta (fore-aft) during a "diching") could plausibly break the toilet from it's mountings, it moves forwards, fracturing the panel, and releasing it.
Obviously lots of other things like overhead storage bins etc might also be damaged and small pieces become loose items in the cabin, many "free agents" as it were, some floatable, some not.
Now, if the fuselage breaks open at one or more points (ruptures during a ditch sequence - which would take say between 3 and 5 seconds from "splash" to "floating stopped") many of these "frangible & floatable" items may find their way outside before the whole thing sinks.
Any honeycomb core items that remained inside would be crushed by pressure as the sinking proceeded, and thus become non-floatable, so even if they somehow later escaped the fuselage during the trip to the bottom, they would also go to the bottom.

So, the likelyhood of any honeycomb panel "getting outside" in a "floatable condition" is very low, because it would have to "get out quickly", before the aircraft sunk too far, perhaps only 40, 50, 60 feet max, before it was "crushed".
The only way it could do that, in the short time available, would be via a breach in the hull very close by.

Now, this panel is next to the door. This raises some interesting possible sequences.
(1) The door "springs open" due to door frame distortion = very unlikely.
(2) Fuselage side ruptures adjacent to the "very strong" door frame itself = plausible = likely.
(3) Door is deliberately opened by a person = given what we think we know, highly unlikely, but not implausible.