I agree with this.
The Alliance see Garrosh as the leader of the machine that is smashing them, as a lifelong enemy, he must be stopped. Status quo.
The Horde see Garrosh as a hot headed youngster who has alienated everyone around him and they need to remove him. Enter a rebellion.
To me, Vol'Jin, Baine, and Lor'themar should never even consider the Alliance for assistance, as they are the hated enemy and if you let them in, you are jeopardizing your own people. The "enemy of my enemy is my friend" does not work here.
On the flip side, the Alliance would be foolish not to capitalize on the inner turmoil. Offer some assistance, weapons etc, just try not to offer personnel. Let your enemy fight amongst themselves, kill themselves and when the rebellion jumps off, prepare to strike.