Kyle: I've been to that place where you're living. There's some serious Stepford Wives vibes going on there, you know that, right?
The Stepford Wives is a 1972 novel written by Ira Levin, which was subsequently made into movies in 1975 and 2004. In the novel and the movies, the wives of the town of Stepford have all been replaced with lookalike docile and subservient androids. In this case, Kyle is concerned with the cultlike nature of the 4400 Center where Shawn is staying.