That still doesn't change the fact that they saved their race.
I'm telling you again, they've allied with the horde because their former Ranger General was there, giving them support when they needed it the most. They could have asked Alliance for help, they didn't have chance to. Lordaeron was destroyed, their kingdom was surrounded by Plaguelands and population decimated by Arthas. They needed an ally at that particular moment not later.
Beside, remaining Alliance forces (Dwarves of Ironforge and kingdom of Stormwind) knew what happened to Quel'Thalas, they never bothered to send reinforcement or any other sort of support.
As much as you hate it it's still a fact.