As you are well-familiar with Salinger's works I'm curious what you think of a long-held opinion I've had:

That the novella Zooey is kind of a repudiation of Holden's "philosophy" at the point he was at in his life. That when Zooey is having the second-to-last heart to heart with Franny, that he is speaking to her about many of the "flaws" she has that Holden has as well. It's been awhile since I read it so I can't back it up with a ton of details, but memorably that "its none of (her) goddam business" that her professor musses his hair before a lecture.

Like Holden, Franny is written to be "soulful" but dealing with an internal conflict with an ideology about people being genuine/authentic. in Zooey, Salinger sorta clears the air that both Franny and Holden's thoughts are NOT to be applauded, but also not to be taken as "this is a character you should not empathize with." Franny and Holden are written to be flawed but beautiful people (which should be obvious just from reading Catcher). They aren't finished products of people but, contrary to what so many people believe, they are not "meant to be hated."