Your theory makes sense and is plausible.
My only question is:
Where is the debris?
You can bet that by this time, every square inch of the Indian ocean has been mapped by satellites.
If that plane went into the ocean, it would have created a huge debris field. Either tenders were brought in in the earliest days and cleaned up the debris field, or the plane never went down in the ocean.
I would hate to think it was the former as it would bespeak of a conspiracy so massive as to be worrisome. If the latter, any answers will not be pretty.
Not if the plane was carefully scuttled and the fuselage sunk intact with all the floatable seat cushions and whatevers still trapped inside of it.