Intel 101
The captain immediately did exactly what he had been trained to do: turn the plane toward the closest airport so he could land.
From the point of last contact, RMAF Air base Kuantan would have been on the reciprocal track back towards KL. If you look at Google Maps this will be evident. This was without doubt the nearest divert airfield with Fire Services.
Kuantan is a Fast Jet Base which has Mig 29, F/A-18D and other FJ assets.
Langkawai would have been at least three times the distance and around 60-70 degrees of the reciprocal track to Kuantan.
A "land as soon as possible - nearest divert" wouldn't equate to Langkawi or Penang airfield for that matter.
Good post, however imho unlikely.
Cheers