Our site redirect product is really only designed to provide whole-site redirection from WordPress.com to a functional mirror of your site if you have migrated elsewhere (usually to a self-hosted WordPress.org installation).
So functionally, if you still had your site:
Set up with us with all of your content, but you had set up a new WordPress.org site:
On some other server with a WordPress.org installation, Site Redirect is designed to automatically provide a 301 redirect for any specific page requests to your new site.
So. In this example:
Would get a 301 redirect to:
Now if for some reason you did not have "page-one" set up on http://saintjeandegarguier.com, then it would of course result in a 404 error, however we would still send requests to it.
I hope that clears things up.