"If everyone is publicly saying it disappeared at or near the IGARI waypoint they'd need a very strong suspicion or other evidence to divert the SAR effort so far away surely?"
Agreed, I posted the same thing earlier. Also, if the aircraft was back on a Westerly track, why are they not searching the dry land on Peninsular Malaysia (I don't think the aircraft would have detoured round Singapore?!!). There is a strong suggestion here that they have a lot more information than that being announced. Which would be normal.