Hi,
Well, that code is for the Lite version, but it does something completely different – it limits the results to posts 1, 2 and 3 by their IDs. It is only a sample code snippet.
It should be doable via custom code, but I need to know how B2BKing sets the product visibility. If it is a custom field value, or a taxonomy term, then there very simple non-programmatical solutions.
If it uses a custom table or some other method, then all I need to know is how to check if the item is visible to the current user, using the product/post ID, and I will suggest a custom code. Let me know if you have any information about that.