Essentially none of the components for the requested ILS DME 09 approach (localiser, glide slope , Dme) were used by the pilot to fly the approach ?
That seems to about sum it up. The evidence suggests that the pilot had just selected "direct DND" on the 530, rather than entering the ILS as an approach, then forgotten that and taken the pseudo-DME reading from the 530 and used that as the distance from the localiser DME.
I don't know how Jepp/Garmin depict approaches in the UK, but in the US the obvious thing to do is select the ILS, then switch to NAV mode when established on the localizer inbound.
There are plenty of approaches like this in the US, not to mention much higher terrain, but I don't think anyone has ever said they are fundamentally unsafe. But it does help to select them correctly.
Could be that the "GPS is the devil's own handiwork" view of approach design, which seems to reign in the UK, makes people less familiar with doing approaches in a hybrid fashion like this. In the US 99% of pilots would use the GPS to fly to DND, rather than the ADF (because hardly any aircraft have one any more) - and this is explicitly approved by the FAA. But the report makes snooty remarks about this not being approved.