This whole debate is very applicable to the world of software. In fact, I believe that computer programs are legally considered to be works of literature (although I'm sure it's more complicated.)

The authors argument is roughly "you're not allowed to fork my proprietary project because it's proprietary," while the school librarian has an opinion that I would consider to be more copyleft. I tend to agree with the librarian.

I think that writing a book that uses major plot details from another book without copying them verbatim is not illegal. That would be analogous to writing a program that does the same thing as a proprietary program. I argue people should have the right to do this for books just as they should have the right to do this for programs.