I agree with the earlier post that if they are searching The Straits of Malacca, they must have something else which they don't want to release. That would be 1.5 flying hours back from the Southern tip of Vietnam.
The other thing not being addressed (Excuse me if I missed a discussion, this is a long thread) is the missing 5 passengers. Malaysian went out of its way to confirm that the checked bags of these passengers were offloaded. But FIVE no-shows is an awful lot? Who were these people and what was the routing of their tickets? Did they turn up to claim their checked bags or did they "Disappear". If so, what was in those bags?