Thinking latteraly ,SOPs if they are Indeed written for this type of equipment should perhaps reflect the unique nature of PNG bush flying. It seems the undesirability of nuisance warnings should be acknowledged,and a procedure that formalises the deactivation of GPWS under strict conditions be promalgated.
Wether or not this proves to be part of the causal chain in this accident only a full investigation will determine. The essential reality is that lessons be learned.
CFIT events are always perplexing,and here it seems none more so than in this accident.