While you're technically correct, incidents like this can be actionable under tort law and damages claimed to compensate for income not earned.

If you always earn $10,000 a day in profit from customers entering your shop, and someone barricades the entrance to your shop for one day, I don't think you'd have a hard time in court showing that you "lost" $10,000 that day.

This is quite an incorrect analogy, as in this case nobody prevented anyone from buying the books.

Comparsion to a store, earning $10K every day, then "losing" 90% because someone spreads a gossip that your store sells very low quality stuff, would be much more appropriate. Just an old plain defamation.