I get what is being said here, and I somewhat agree with it. Telling people something bad happens doesn't actually do anything to stop a bad thing from happening. And yes, having everyone use HTTPS all the time would be a better way to combat firesheep. But the fact is that not everyone is going to do this unless it becomes the out-of-the-box standard for web browsers.

However, blacksheep is not useless as the author suggests. If I am in a Starbucks using wifi, I might be using HTTPS for everything. I also might be using blacksheep. In that case, when alerted that a firesheep user is around, I might make use of the DoS tactics found here: http://news.ycombinator.com/item?id=1884176. This allows me to protect other less tech savvy users from firesheep evil-doers, and more importantly, screw with people who are screwing with people.