If it was they should put some sonar down there, should be pretty easy to find..I know the saying what goes up must come down but I would think what goes down will eventually come up again, the plane would rise to the surface, from what I hear its shallow water in that area some parts of the plane would surface I would think
There should be a debris field somewhere...It’s odd to find an oil slick but no trace of ANY debris, large or small? Doesn’t make sense...
Most of the aircraft, aside from the furnishings such as seat cushions, plastic trim, and scullery, are made of aluminium, titanium, and steel, all of which are heavier than water. Those items lighter than water, if worked free, may rise to the surface. The heavier than water bits, probably ~90% or more, will not rise off the seabed unless lifted.
Re: oil slicks, I too am rather dubious about the slicks spotted having anything to do with the aircraft. The photo of the slick sighted shows some yellow residue which would not be indicative of a kerosene spill, though it could be turbine oil from the engine lube system or hydraulic oil. There are many small tankers traversing this area, and they still do dump their slops after tank cleaning.