(sorry for my poor english) I imagine bio's titles are used for the user full name. So I think it would be nice the ask the user's bio title on registration, instead of using the user name as title.
I did it in a simple way, but a better implementation should offer this as an configurable option.
I added this in bio_user_register_form()
$form['bio_info']['title'] = array( '#type' => 'textfield', '#title' => t('Name'), '#weight' => -1, '#maxlength' => 64, '#required' => TRUE, );
and changed this in bio_user_register_submit()
$node->title = $form_values['title'];