@webgroup *from the other post* at the moment no, though there is nothing stopping you adding a htaccess file to prevent direct access to that directory. The membership plugin access the file directly through the file system on your server and then serves the image / file via the plugin – so with the plugin enabled no one should need to access the image directly.
The main reason is because not everybody (including me 
) use apache, so neither of those methods would work on my server.