RE: "Better still are you sure it wasn't a UFO he saw and decided to just go on a bit of joy ride, yeah, let's make sure our plan B includes a good swath of Malaysia and just for giggles we'll turn off the transponder. That'll put the meteorite/UFO/bigfoot off for a bit"
Just sayin... there could be a less-than-super-duper-brilliant Plan B in the FMS. That could have the left turn, and be what the investigator leakers are seeing.
Plan B becomes active when executed. An emergency is the reason. Not necessarily UFOs or BigFoot. Maybe from smoke. Or electrical mechanical malfunction. And the comms and transponder fail then as well as ACARS. and off we go (left) on AP.