This really isn’t a thing. While garrosh wanted to attack in the tundra not only did he not he also sent alliance troops back to there keep, at the same time the alliance was actively attacking the horde in the fjord.
As far as cata goes garrosh does nothing to start the conflict varian declared war on thrall and attacked the barrens and mulgor before the shattering at which point garrosh had done nothing to the alliance as he was dealing with abunch of internal horde conflicts.
The idea that the horde started the cata conflict just doesn’t have any legs to stand on at every turn it was the alliance.