While many other bans, especially on social media, seem to me to be quite nuanced, banning the re-sale of an old book is insane. Who does it hurt of this book is still sold? There are good reasons not to publish it for children anymore. There are good reasons not to stock it in a book shop. There are good reasons not to lend it to children in a library. But why would you prevent two people from selling it between themselves at a (digital) marketplace?