of disorientation when flying VFR in what is clearly an IFR environment.
Let's get this back in perspective. A twin engine helicopter will have blind flying panel. Should the pilot be competent to fly that panel and has a rating their is nothing to stop him flying VFR in VMC at night. Training schools do it all the time.
Irrespective of whether one regards flying offshore at night without a discernible horizon as VFR or IFR they will still be VFR on the approach and landing.
There would be severe disadvantages of filing n IFR flight plan which would involve diversion fuel etc. so a VFR flight plan is quite safe as long as the weather is OK.
It would have made no difference to this flight, as far as I can gather, whether he flew IFR or VFR.