I'm not entirly sure why this rule did not get generated, since Security Assist should have created this rule if you ran the Security Assist Wizard. But if you want to create the rule, click the rules manager button, click the + button and you will need to add two conditions. the first one is restrict if the $_SESSION["VisitorEmail"] is equal to empty and another one that allow if VisitorID does not equal empty.
Let me know if you still have any questions.