Nope, the line you found seems to be some basic preliminary query. Selection of users for display in table seems to be handled by WP_User_Search
class. Luckily it can be hooked into easily.
Try this (changes order to descending):
add_action('pre_user_search', 'change_user_order');
function change_user_order($query) {
$query->query_orderby = ' ORDER BY user_login DESC';
}
PS I am not sure if this can interfere with something else, so might require checks to only run on that specific page.