Hi David and Adrian,
Sorry for my slow response; the above extension was added to our production server (the live wiki) last night and you should be able to use it now. Our technical administrator did have some concerns with the extension: mainly, in no way should this extension be used to manage access to secure or confidential content. I don't think this is a problem for your goal of hiding editing or formatting elements but please be advised that it does not create any true permission-based security and all content should be regarded as being discoverable on the wiki. Because of the possibility of this extension being misunderstood, we generally ask that you do not heavily promote its functionality beyond your project (and to generally remind your users that confidential or private information should never be added to the wiki). Please let me know if that makes sense or if I can provide further info.