its not really counter advertising becuase your not targeting the publisher, your expressing your opinion of an individual author. Suggesting the boycott of an author isnt really that different than a peaceful public demonstration of a bunch of peta people gathering in front of a hot dog factory shouting boycot hotdogs, save the pigs. A few of the posts here can be considered as personal attacks, and should probably be a little more discreet about expressing their opinion, but i havent seen any laws broken yet.