Telepathy?  Jedi don't have telepathy. 

Worse still... if there was some sort of Telepathy thing going on Vader and The Emperor would be in fits laughing on the floor trying to find the strength to issue orders to the fleet to wipe out the sanctuary.

I also think it would take a bit longer to get the word out.  After all, the story involves the "last of the survivors".  If the sanctuary were put into play instantly entire orders would be showing up instead of the few survivors of each.