This add-on is a great way to inform your user base of specific rules which may be in-place on some sections of your community and not others. Overall, it works how it is supposed to and the developer is very responsive to support inquiries.
I had an issue that made it possible to bypass the rules screen in certain scenarios fixed on the same day as I requested support. Absolutely recommend!
The resource listing is very clear in the features offered. We repeat that the add-on allows you to configure "per-forum rules", the screenshots all only show specific forums having rules attached to them and are unambiguous in this regard. Indeed, the statement you've quoted also indicates the same. The 'forums' are the individual forums, and the board is the XenForo installation itself, and this is the same terminology used throughout XenForo's options. We've left no ambiguity in the resource listing or the screenshots, and made no suggestion that the add-on will force users to accept rules before viewing the board itself. We encourage all potential customers to contact us with pre-sales questions, either in the thread or via our support link.