Chill
Reading your post on Kota Bahru and Kuala Terengganu as possible landing site. Adding the CCN theory of the plane turning across the north of Malaysia with KUL as their aim. What about Penang as the target? An active airport with cargo traffic at night would keep the airport open, big enough runway and should they not be able to make it have the sea around them.
My thought on the crossing to the west towards the north missing the Titwangsa range at the highest point and crossing at a less densely populated area (just in case).