Using .htaccess to restrict access

I just thought some more about this and will kindly suggest an additional change to the check.

# Allow Opt-Out
<Files "index.php">
 <If "(%{QUERY_STRING} =~ /^module\=CoreAdminHome\&action\=optOut(?!.*module\=)(?!.*action\=)/)">
   Require all granted
 </If>
</Files>

If someone wants to know why, take a look at this:

In short, someone could craft a link that matches the regex but does request completely different than the OptOut.