You probably missed the part where soldiers were sent to rescue horde soldiers taken into the plague.
That was a battlefield. She had allready plenty of horde corpses killed by alliance at disposal.
While on the other hand, Baine personnaly killed many horde soldiers for the sake of the alliance. And thrall and Saurfang allied with Jaina who just invaded a city to kill the king of a nation just because they might have joined the horde, did the exact same thing.