Things are certainly easier these days, then with normal season. There's plenty of reasons for this, and I'm sure there's few more which I won't mention. First, there's no spectators on site. Moving race for day with 100.000 people there (ok that's just Kitzbuehel, as other races it's more like 5000 to 20.000) is not easy. Next thing is, hotels are normally operating, which today they are not. This means, they have space for WC tour from let's say Thursday till Sunday, and on Sunday afternoon new guests are coming. Moving race to Monday simply won't work, as there's no space for everyone to stay there till Sunday. Same goes for ski resort. Ski resorts are losing money, when half of resort is closed, so extending this closure for another day is not really much of an option. Today, hotels are closed, ski resorts are closed, and there's noone skiing there and noone coming to those hotels, so it's fairly easy to extend for another day.
Contrary to Italy, in Switzerland it's season as always, and everything is open, and I guess that's the difference between moving race to Monday or going home hoping to find replacement date and place somewhere later.