The report gives a concise and accurate account. As an airline captain the following is clear to me:
The Citation pilots were an accident waiting to happen. Their arrival in to Linate in Cat lll conditions without being Cat lll rated should not have been made. Having done so it should have been queried by the airport authorities and their departure not have been allowed until the visibility improved, with an investigation as to why they made the approach.
The controllers were under a high work load. However in Cat lll conditions both controllers and (qualified) pilots are aware of giving greater separation between aircraft, in the air and on the ground. The controllers should have asked the Citation pilots to report passing specific taxiway signs. However these signs were themselves inadequate.
The airport authorities were also allowing the airport to be operated in Cat lll conditions with inadequate taxiway signs and without a ground radar which had been available for installation for many months but was still boxed up, presumably to save money. Certainly the ground radar is not essential as long as the other factors in this accident were not there. In this case the ground radar would probably have prevented the accident, but only if it was being operated correctly.
It will be interesting to see where the investigating authorites put the blame for this tragedy.