If it turns out to be deliberate action by one of the pilots there is nothing to stop the same thing happening again , might be time to run aircraft as drones as so many accidents are due to pilot error.
Would you fly on a pilotless plane ?
Surprised that civil aircraft do not require a transponder uploading heading , altitude and airspeed along with GPS to satellite every few minutes rather than a black box with no guarantee of ever finding it overflying deep water.
A battery that lasts for many months and a more powerful signal would add a tiny cost to such an expensive thing as an aircraft , the GPS tracker in my car alarm seems to do a better job for a few hundred pounds.
Even drones have pilots. just thousands of miles away....