<?php

is_admin() && add_action( 'pre_get_posts', 'extranet_orderby' );

function extranet_orderby( $query )
{
    // Nothing to do:  
    if( ! $query->is_main_query() || 'people' != $query->get( 'post_type' )  )
        return;
    $orderby = $query->get( 'orderby');
    $query->set( 'orderby',  'data' );
    $query->set( 'order',  'ASC' ); 
}