Can someone point to a credible primary source that in fact there is any search activity in the Malacca Straits ? Just because the aircraft are BASED in Butterworth (on the Malacca coast) does not mean they are searching there. I can imagine the apron at Kota Baharu getting rather cluttered, so a base 200km away might be more suitable for the long-range P-3s.
Why they are at RMAF Butterworth is because:
"The base is home to:
RAAF 324 Expeditionary Combat Support Squadron (324 ECSS)
RAAF 92 Wing Detachment Alpha"
RMAF Base Butterworth - Royal Australian Air Force