In Catch-22, the mechanized efficiency of modernity and the madness of war keep many of the characters isolated from one another. Though they hang out together, none of the men really forms meaningful, lasting relationship. They often suffer from profound loneliness and insecurity, or find meaning only in material things. Whenever there is a fellow who is slightly odd, he becomes marked as a target for the others, which only serves to increase the victim's sense of alienation.
In choosing to isolate himself, Major Major chooses wisely; only in isolation can he maintain his morals.
In choosing to isolate himself, Major Major shows his weakness and gives up any hope of being accepted into society.