I think you'll also agree that most people in the real world aren't be like the Pattersons and their companion cannibals and wouldn't actually cheer on the horrible emotional affair simply because Lynn got bored. This explains something that the Ridgways probably did soon after the inevitable angry confrontation with the louse who'd upped and dumped her for no reason she'd admit to. My guess is that his angry screed about how she was playing tic-tac-toe could have been the first time the Ridgways had heard the name "Rod Johnston."
Since they probably couldn't bring themselves to trust that situation and probably were concerned that Lynn would do something stupid to Aaron, they appear perhaps to have sent Alan East to play respectability cop and make sure to keep Lynn from getting away with what she did. Since she doesn't like the idea that anything she might be doing would be bad leave alone being seen as bad and since her mother retained her role as primary dispenser of discipline, this forcing him to babysit his sister and could be why Alan doesn't mention Lynn on his website. Having to be bossed around and yelled at when everything she's ever done is correct seems to me to by Lynn wanted to bury the axe in her mother's skull.