How to perform a reliable full permission check?

Our user default permission to create new topics is "grant" on the community node. On our archive sub-boards we are denying this permission for all users. When checking for this permission in a custom component coreNode.permissions.hasPermission("create_thread") returns true though :(

 

According to the coreNode context object documentation of the hasPermission method "This method does not apply to permissions a user can take in a core application. It does not perform a full policy check. It could be used to add permissioned custom functionality to a custom component.".

 

So how do I reliably check / "perform a full policy check" for that permission ina component?