Even if Doomhammer succeeded in conquering the Kingdom of Quel'Thalas, the resistance of the entire kingdom would cost him dearly in time. By the time the Orc and Amani Combined Army captured Silvermoon City and occupied all of Quel'Thalas, they would inevitably have wasted a great deal of time.
By then, the Alliance armies would surely have made their preparations. When the invaders turned their sights on Lordaeron, the Stratholme Region, currently short of troops, would probably have raised quite a few new legions! At that point, even Doomhammer would no longer find attacking Lordaeron so easy.
Moreover, although the combined army of Orcs and Amani Trolls looked terrifyingly powerful, the Orcs had come from far away. They could not possibly have brought enough supplies to sustain a prolonged war. The Zul'Aman Trolls themselves had little productive capacity, so expecting them to supply the entire combined army was simply impossible.
"I think they allied with the Amani Trolls for two reasons. First, they needed passage through Zul'Aman so they could secure a safe landing point and establish a Portal. Second, when they launched their surprise attack on the Kingdom of Lordaeron, they wanted the Trolls of Zul'Aman to hold back the army of our High Elf kingdom of Quel'Thalas, rather than let us pursue them all the way.
"So I believe the Orcs actually have very little time. They must find our main High Elf forces within that limited window and win a decisive victory quickly. Therefore..."
Sylvanas paused, then continued, "What we most need to establish now is whether the Kingdom of Lordaeron is the primary target of this surprise attack.
"If their target truly is Lordaeron City, as Brother-in-law said, then their objective will not align with the Amani Trolls' strategic goal of occupying Silvermoon City.
"That gives