Skoll Shorties

War of Thorns was strictly an agreement plan between Varok and Sylvanas but Varok was mostly in charge of the attack upon Teldrassil but Sylvanas didn't share her full plans either. Doing the quest I remember Saurfang even tells you to spare and get the civilians out of there.

Saurfang wanted an honorable war everything in the War of Thorns was done in his tactics, not Sylvanas'. The moment that Sylvanas torched Teldrassil was the moment Saurfang realized this wasn't going to be a war in his terms.

To Saurfang the war against the Night Elves isn't pointless. They're a daily threat to the Horde and also refuse their resources. Sylvanas twisted the Horde's ideology to work for her. Saurfang and his perspective of the Horde is a far more honorable one than Sylvanas'.