The encounter may appear after the player finishes the Tenpenny Tower quest. There are two different versions of this note depending on whether you chose to let the ghouls into the tower or not. Version A appears if the Lone Wanderer has helped Roy Phillips and his followers into the tower. Version B appears if the Lone Wanderer killed Roy Phillips and his followers.
Brothers and sisters! Roy Phillips and his righteous band of diplomats have been massacred by the smooth-skins at Tenpenny Tower. It is time we arise and show the world that Ghouls are people too, that we have the same rights as everyone else, and that we won't placate and bow down to their bullshit any longer! Bring lots of firepower and righteous hatred with you. We amass at Warrington Station. The revolution has begun!