Not sure that lack of multilat can be called dangerous - after all in the entire history of the North Sea there has never been a collision, but plenty of other ways to die in a helicopter. So if it is dangerous, (and danger vs safe is a sliding scale not an absolute) then there are far more dangerous issues that perhaps should receive your attention. I suspect you have an ulterior motive/hidden agenda!
I believe the problem with Multilat is not of NATS making but rather its very difficult to get beds and trips offshore for the workers who would fit the kit. You could argue that the Oil Companies should be prepared to sacrifice production time for this safety kit, but there is of course no legal requirement for them to support NATS, and bearing in mind my first para, there is no great safety case. With TCAS I and in the near future II making its way onto the N Sea, the case is further weakened.
Of course I would like to have Multilat, but in the great scheme of things its not top of the agenda.
HC