Honestly they didn't give any reason for the delay other than at first saying the aircraft under preparation and then finally there is a fault which they mentioned at around 10am, they didn't cancel the flight until 2pm i believe
If out of hours i do not think the ground staff could not do anything until the office opens in Jakarta other than place you on a later Qatar Flight.
There wasn't a lot of choice from CGK that day, SQ,TK where fully booked, Emirates and Etihad they can't use or transfer too , which basically left transit in KL,HKG or Sin and the preference was to use One World.