I think we all accept that the crash site was almost certainly in fog. It is
also quite probable, based on Holbrook,that the aircraft approached the Mull in legal VFR. As far as I know, no one knows the aircraft speed at the Mull waypoint. There is no ADR and the aircraft was not being tracked on radar.
I ask again. How were they negligent before the Waypoint?
It is the bit in the middle between the Waypoint where they were (probably) VFR and the crash site where thet were (almost certainly), IFR, that bothers me.