I think what we need to do is not speculate on this particular accident because at present we don't know exactly what went wrong.
What we should be discussing is why in this day and age there are non-IFR pilots flying around Australia (and the world) in single engine, non-IFR aircraft, single pilot in IFR conditions.
They are flying in NGT VMC conditions but without ground or celestial illumination.
Flying off the coast of Australia with no moon is IFR.