Holden is at a very low point in his life when he seeks out Ackley in Chapter 7. He has just had a fight with Stradlater, and seeks out Ackley for comfort. Ackley, however, is only interested in what the fight was about, and will not give Holden permission to sleep in his roommate Ely's bed, even though Ely is always gone for the entire weekend anyway. Holden is "annoyed" at Ackley's insistence that he "can't just tell somebody they can sleep in (Ely's)...bed," and he feels "so lonesome, all of a sudden...(he) almost wish(es) (he) was dead." His depression is extreme at this point, and he has nowhere else to go, which is the real reason Holden is so wounded by Ackley's lack of hospitality.
It is ironic that Holden is so offended by Ackley's behavior. Ackley, like Holden, is a social outcast, and Holden, along with everyone else, is not very nice to him. In Chapter 3, when the tables were turned, and Ackley wandered into Holden's room just to hang out, Holden showed his irritation at Ackley's presence, treating him with rudeness and sarcasm. Even when Holden, in need of company, comes into Ackley's room after his fight with Stradlater in Chapter 7, he treats him with contempt after his initial civil overture. Although he at first asks nicely if Ackley would like to play "a little Canasta," when he is turned down, Holden thinks in his mind that Ackley is "even more stupid than Stradlater," and when he is denied permission to sleep in Ely's bed, he makes a comment deriding Ackley's hygiene, complaining,
"This room stinks...I can smell your socks from way over here. Don'tcha ever send them to the laundry?"
Holden hates phoniness in others, but in many ways, and especially in his relationship with Ackley, he is just as hypocritical as everyone else. He is indeed wounded by Ackley's lack of hospitality, but has proven himself no better than Ackely when he is the one who has the opportunity to be hospitable.