Ok, I've read it and I'm not impressed. The post on hexbear tries to act as if they were seriously considering the anarchist point of view, they are constantly being disingenuous.
The biggest point of critique againstEngels is that he is effectively strawmanning anti-authoritarians, by using a definition of authority that differs from the anarchist definition in a fundamental way. While the hexbear author acknowledges that fact in the beginning and seems to take the (IMHO flawed) definition of the anarchist's critique at face value, he repeats the same mistake that Engels did and takes Engels' definition as the only logical one.