Yeah, this is going to be a pretty sticky change. Take a structured section for example... what if a parent node was created by an different author? We can't remove that from the tree or the structure will break.
One option would be to always display the entry, but grey out / not make clickable anywhere we're retrieving entries.
And to be consistent, we'd probably want to take the edit users permission into account, too.
At any rate, thanks for bringing it up... it's on our list to address.