Fyi:
ADS-B is only available on the L Transponder on the 777 (with standard fit).
As soon as the R Transponder is selected the aircraft is unable to send ADS-B info.
Disabling ACARS (both VHF and SATCOM) is very easily done via the COMMS pages.
Would be interested to see the parameters of the engines that RR received for a good view hours.
If someone has punched in LITEX & GIVAL into the FMC there is a good likelihood that incapacitation isn't on the cards, more a considerate attempt to go somewhere.
FYI: (that airway is used lots by all airliners to transit over Port Blair towards NE India, VOMF AND VOCF FIRs