I don't understand the purpose of this code, because whatever it protects, could be easily accessed.
I've probably not explained it clearly by the sound of it.
At present, using minibb, you can create a forum which is closed and only visible to those users that you specify. All other users are unaware of its existence.
That's fine and very useful but I was asking whether it was possible to specify the ability to specify which forums are visible in a different way which was that they were visible to everyone, just like a normal open forum, EXCEPT for a list of users which you specify.
Why am I asking about this? Well let's say just as an example that your forum site has 10,000 users. One of the forums is just for admins and mods and you create that as a closed forum and just make it visible to those users, perhaps there's just 10 of them so very easy just to input the 10 ids.
But perhaps one of the other forums on your site is for, let's say, those over 18 only and your site has, again let's say as an example, just 50 users who are under 18. So, you want to make that particular forum not visible to just those 50 users. OK, you could do this by creating a closed forum and specifying 9950 user ids as being able to view it but that would be a crazy way to go about it. On top of that you'd have to keep updating the list as new members joined. So, I was asking whether it was possible to define a forum that was open, i.e. visible, to everyone EXCEPT for a list of defined user ids. Please don't take the example above literally, it's just a simple means of trying to explain the concept.
Anyway, I can try coding it for myself, I just thought it was worth asking if there was already a way of doing it.