It's all very well to say that pilots should operate by the rules, but when you have people with a commercial interest getting into the act with instructions to pilots to trip warning breakers so as not to upset passengers (who can hear EGPWS) or worse, interfering via maintenance so that the equipment conveniently becomes unserviceable, what to do?
This has happened in PNG in the past. I had more than one argument over this very thing a few years ago and quit rather than be complicit in allowing it.
Not just EGPWS but such basic requirements as current GPS data bases and TAWS does not get updated. A bit like those infamous last words from the Mexicans just before they drilled in ("shut up Gringo") one classic argument I recall, the guy said - in defence of GPS data bases over 10 years out of date - "the mountains don't move".
Not saying that this caused this particular accident, but such is the culture in that part of the world.