"So nothing to do with being a VFR pilot in IMC then?
"
Correct, it was nothing to do with IMC. The JFK jnr fatal was in night VMC. He lost the horizon over the sea due to haze, and not being IFR trained, suffered a classic SD episode. The report stated that if he had tracked closer to the coast where many lights were visible, instead of direct over the water, he would have had sufficient visual reference and been ok.