The post misunderstands how the permission system works.
Giving access to a file via the Open and Save panel is an explicit declaration of consent.
Because the panel is provided by OS itself, the app doesn't get access to the item until the user has selected a folder or file through that panel.
No, this is definitely a bug. The Privacy and Security panel is part of Settings, which is definitely part of the OS. Saying the Open and Save panel somehow has priority suggests that the Privacy and Security panel is not looking at the same parameters as the Open and Save panel, ergo a bug.