It is at least 200km closer than Langkawi. The flight path was also close to Kota Bharu, so one theory does not exclude the other.
Maybe somebody with more knowledge of an autopilot can offer some insight: what happens is you overshoot your programmed target? With it go in a holding pattern? Would the autopilot disengage? Or will the plane continue on its course?
Whether or not it would, I suppose, would depend on how it was programed.