The term "Permanent URL" is just that, a permanent URL no matter what the name changes to, this URL will always allow you to view that page with that unique URL. A permanent URL has all the same properties as a regular URL; its the same exact page with a different way to access it, so there should be no reason why it would have different permissions or properties.
As Roman stated, if you want to share a URL for reviewing/previewing purposes, the use the Preview URL. This preview URL can change especially if you have versioning enabled. If you save the page and make a version and send out that preview URL, then make another change (version) that preview URL will no longer be valid as the current version has taken over.