Shadoko, you may be right that the bodies recovered were those not seated. However, on the old thread a fellow involved in recoveries from water suggest that dead bodies seem to work their way out even from tight seat belts when you have water to work with. They even work their way out of their clothes much of the time.
Given how small the pattern is I suspect those recovered may have been in seats such as those recovered. But they did not float to the surface from a seat still attached to a large piece of fuselage.
I find it interesting so many were not sitting and not strapped in. Were they holding a dance in the aisles for entertainment? It's another of the surprises associated with this accident.