"The best thing, though, in that museum was that everything always stayed right where it was. Nobody'd move."
Holden likes the static nature of the museum. He likes the fact that the exhibits stay the same. It feels comfortable and familiar to him. He likes the unchanging nature of the museum, because it is so different than what he is experiencing on a personal and real life level. His happy childhood is no longer, because he is growing up. His brother died years before, and Holden's entire family dynamic has changed. School is changing for Holden too. Classes are getting tougher, and he just can't seem to stay in school. Holden is scared by all of the change that he sees happening around him, and he wishes that life could be more like the museum. Static, predictable, unchanging, and comforting. I have to admit, while I don't like Holden that much through most of the book, I sometimes completely agree with Holden's attitude on this one.