It's definitely the right call to cancel Auron, it's meant to get 30 centimetres of snow tomorrow in the ski station itself. Admittedly it might have worked, but if it doesn't you have to finish in the valley and the stage is immediately ruined.
However, it's a shame that they aren't trying to go all the way up to Madone d'Utelle. Yes, at a predicted snowline of 1000 to 1300 metres (depending on which forecast you look at) it's not guaranteed you can make it work, but with the snow mainly in the morning and the temperature slightly rising in the afternoon you could always opt to move the finish down to where it is now as a plan C if things look bad in the morning.