Put forward by some theorists as a "what if" " or a "maybe" but never corroborated. It may appear in some conspiracy circles but no mainstream blogs of forums I have seen".

My theory is they were simply covering their incompetence. MAS ops (2 phone calls only iirc), ATC and the military all asleep at the wheel.

Only when Jay Carney from the White House and Inmarsat publicly said 'we think it went down in the southern Indian Ocean' did Malaysia come to admit it happened.

But... in the recent report they say they knew it was 370 crossing the peninsula and deemed it not to be a threat!
Why all those countries who wasted their time and significant resources in the South China Sea don't call them out on this obvious inconsistency is beyond me.

So take your pick. They knew it from the the out set and failed or could not do anything and hoped nobody would notice. Or they were alsleep at the wheel and it flew past and only noticed it on radar looking at recordings and try to pretend they knew it was 370 all along, hoping again that nobody would remember they let everyone look in the South China Sea for a week or so.

I'll go with incompetence.