I understand your position, but it's a serious problem for me.
I think if you would look at the current code you would see that the user code for Zikula is very like Postnuke, but some user database changes have been made because they have better separated the login process from user profiles.
The info on Postnuke.com is poorly worded, probably because of language issues. The project changed it's name to Zikula and continued with planned code changes, which would have happened even under the Postnuke name. The project didn't have control of the Postnuke country domains around the world and that was a big reason for the name change. It's not a fork or new project.