The reason for using the Confirm Signatures option is to provide some assurance that the person signing the petition is who they say they are. It is not there to protect against robotic spam, but to protect against people misrepresenting themselves. If that sort of filter is not something you want, you should probably not turn that option on.
That said, if you want unconfirmed signatures to show in the public list, comment out line 150 in class.signature.php so that it looks like this:
// $sql_context_filter = "AND ( $db_signatures.is_confirmed = '' OR $db_signatures.is_confirmed = '1' )";
Signed petition emails from unconfirmed users still will not be sent out, but your public signature list and numbers will be incremented.