The point is that the ac commander has a responsibility to manage the risks of any landing site. As complex as yacht-heli ops are, a yacht deck environment is eminently controllable - as are the O&G industry's decks - it's a matter of having a proper safety-focused approach to doing it and no-one should land on a deck unless they know there is a system to prevent any possibility of a FOD occurrence like this.
This was a tragic occurrence but no-one should convince themselves that it was unavoidable. Learn from it and move on.