If you infect 5 random people on a flight of 200 that's a bad problem, if you infect 5 random people out of 50,000 that's a terrible problem. In terms of containment it is 250 times worse.
In the first instance the health authorities have some chance of back tracking over contacts and containing the spread, in the second even if you know it's due to the match you've much less chance of containing the subsequent spread.
A pointless match against Italy (they exist in the competition solely to create 3 matches a weekend) versus still unlikely but possible community spread of this virus. It's not really a choice - cancel the match.