Findings
Does not protect any uploaded files, or files that are not php
Does not protect what posts have been made and their content via bypass.
Does not work unless you are using mutisite and it does not protect the network site.
Reason for the 'Potentially unsafe' result
The plugin contains or is likely to contain a vulnerability which could be exploited by an end user and which would compromise the site’s confidentiality, integrity or availability:
Does not block xmlrpc, so you can find out info about posts that are meant to be protected.
Here is an example rpc to see if a post exists or not.
POST /wordpress/fred/xmlrpc.php HTTP/1.1
Host: 127.0.0.1
Content-Length: 243
<?xml version=”1.0″?>
<methodCall>
<methodName>pingback.extensions.getPingbacks</methodName>
<params>
<param><value><string>http://127.0.0.1/wordpress/fred/2013/08/09/hello-world/</string></value></param>
</params>
</methodCall>