I disagree. If you value the contributions of comments above your or your aggressor's ego - which ideally you should - then it would be a good decision to make others aware that this behavior is going on, even at the expense of providing positive reinforcement. After all, the purpose of the karma system is to be a method for organizing lists of responses in each article by relevance and quality. Its secondary purpose as a collect-em-all hobby is far, far less important. If someone out there is undermining that primary purpose, even if it's done in order to attack a user's incorrect conflation of karma with personal status, it should be addressed.