I recently had reason to verify that an avatar who was a member of the land group with the required abilities could not stand outside a parcel from which she was banned and return objects from the parcel. I had assumed that this would not be possible. I was surprised that it is possible.
This is obviously a security issue and should be fixed. If an avatar is banned from a parcel, they should not be able to do anything to objects on that parcel.
Why would it matter? Would a banned avatar be a member of a land group? It could happen by mistake. The group owner and that avatar could have a falling out, and the owner could ban the avatar and forget to remove them from the group.