If the overreacting author is unknown (and a bit insane), all the resulting publicity will be bad, as it will probably be if an author tracks down and stalks someone who gives them a going-over on Goodreads. In the latter case, though, the author may be seen as bravely standing up to ‘the Goodreads bullies’. The democracy of the internet. Authors hate that, in inverse proportion to their success and/or talent.