Yeah I was pretty confused about that too... they are just there. Being quiet.. and plotting something evil!?!?
They have a flamethrower, a chainsaw, good god sherman you may be on to something!
It is a bit odd that they never commented on how they really were at SFK. Perhaps they either realized it was a lost cause, or just wanted to see the heroes suffer?
I'm guessing the later to be more likely.
I'll go with lost cause at this point since they can't seem to recognize worgen, even if two were practically staring them in the face
Manbearpig
You know, the murloc sisters haven't complained once throughout this journey