I presume standard ICAO SARPHASE procedures where followed?
Precisely. The uncertainty phase commenced soon after Subang was unable to make contact with the aircraft. After all communication attempts failed, the alert phase was issued at 2:40, pretty much an hour after the start of uncertainty phase, and I'm sure all relevant authorities started preparing for a SAR mission. Full scale distress phase was probably declared at/around ETA BJS.
The same timescales happened with AF447, SAR was only launched after the aircraft failed to make contact anywhere beyond its remaining endurance. An overwater SAR mission is a very costly exercise, and diverts scarce resources which potentially might be needed for another emergency. Such resources are not sent off on wild goose chases until at least the basic facts are gathered and analyzed.