I'm thinking a mix of 2, 3 and my own. From all the posts I've read about CB radios, Michael's transmission could have gotten to the tower (19-2 there is a click in the noise after Michael radios the tower). The tower could have gotten his message and sent a team out to find Michael's help and stumbled into the colony like MPK did. Once this new team shows up, they help spring Michael and start a civil war, losing a main character in the mix.