On another message board I lurk at this topic came up, I'll just quote the good part.
To believe the Marxist literary theorists, the reason the establishment teaches books by Salinger (and Orwell, and Lee, and other anti-establishment authors) is to co-opt them and undermine their subversive content. I doubt teachers think of it that way, but getting handed a book in school definitely affects the way students read it. And the way teachers teach it also probably undermines the effectiveness of the book.
Any truth to it? Well, obviously the last coupe of lines are true(ish), but they could be true whether the theory is fact or not. I don't think it's true because it's almost too clever. People that want to censor things don't tend to be that clever.