Gab wohl 2 NOTAMS:

A3028/20 (Issued for LIBB LIMM LIRR) COVID-19:
ALL FLIGHTS ARRIVING/DEPARTING TO/FM ITALY MUST COMPLY WITH THE REQUIREMENTS OF THE DECREE OF THE PRESIDENT OF THE MINISTERIAL COUNCIL OF 17 MAY 2020 ON FOLLOWING AIRPORTS: LIPY, LIBD, LIME, LIPE, LIEE, LICC, LIRQ, LIMJ, LICA, LICD, LIMC, LIRN, LIEO, LICJ, LICG, LIBP, LIRP, LIRA, LIRF, LIMF AND LIPZ, COMMERCIAL FLIGHTS, COMMERCIAL FLIGHTS ON DEMAND (AEROTAXI) AND GENERAL AVIATION FLIGHTS ARE ALLOWED.
GENERAL AVIATION ACTIVITY AND COMMERCIAL AVIATION ACTIVITY ON DEMAND (AEROTAXI) WITH AIRCRAFT HAVING MAXIMUM APPROVED CABIN CONFIGURATION EQUAL OR LESS THAN 19 SEATS, CARGO FLIGHTS AND POSTAL SERVICE ARE ALLOWED ON ALL REMAINING AIRPORTS.
GENERAL AVIATION ACTIVITY, COMMERCIAL AVIATION ACTIVITY ON DEMAND (AEROTAXI)WITH AIRCRAFT HAVING MAXIMUM APPROVED CABIN CONFIGURATION EQUAL OR LESS THAN 19 SEATS ARE ALLOWED ON AIRFIELDS/HELISURFACES/HYDROSURFACES MANAGED/AUTHORIZED/OCCASIONALS, WITHIN THE LIMITS OF APPLICABLE AUTHORIZATIONS IN COMPLANCE WITH THE PROVISIONS OF THE DECREE OF THE PRESIDENT OF THE COUNCIL OF MINISTERS OF 17 MAY 2020
RMK: GENERAL AVIATION ACTIVITY AND A COMMERCIAL AVIATION FLIGHT ON DEMAND ON LIRF IS NOT PERMITTED.
19 MAY 11:16 2020 UNTIL 02 JUN 22:00 2020 ESTIMATED.
CREATED: 19 MAY 11:27 2020

Und nummer 2, wie am Anfang zitiert, 2 Tage älter....

B2520/20 – COVID-19.
AERODROME CLOSED TO COMMERCIAL AVIATION TRAFFIC IN COMPLIANCE WITH REGIONE SARDEGNA DECREE 23 OF 17TH MAY 2020.
RMK: GENERAL AVIATION ACTIVITY AND COMMERCIAL AVIATION ACTIVITY ON DEMAND (AEROTAXI) WITH AIRCRAFT HAVING MAXIMUM CABIN CONFIGURATION EQUAL OR LESS THAN 19 SEATS ARE APPROVED IN COMPLIANCE WITH MINISTRY OF INFRASTRUCTURE AND TRANSPORTATION DECREE 207/2020 AND REGIONE SARDEGNA DECREE 23 OF 17TH MAY 2020.
REF AIP AD 2 LIEO 1-1. 21 MAY 15:14 2020 UNTIL 02 JUN 22:00 2020 ESTIMATED.
CREATED: 21 MAY 15:14 2020

Im Zweifel hätte man sich nochmal vergewissern können. Ich habe auch schon einmal vor dem Takeoff den Tower an der Destination angerufen nachdem das Snowtam offensichtlich völlig unlogisch aussah und "closed destination" bedeutet hätte, es hat sich dann als Tippfehler herausgestellt.