“When you have washed the bodies of a thousand kaldorei burned and broken, when you have fallen to your knees and kissed the feet of a thousand mourning souls, when you look into their eyes and tell them ‘our Horde has changed’ and they believe you, only then will I accept your apology and treat you as my equal.” Tyrande’s voice, edged as steel, pulled the air out of the clearing. “My brethren here may be willing to entertain your empty pledges of justice and aid, but I know better. I have learned better.”
I think that they covered this in the novel. 