add_action('bp_ajax_querystring','sq7_radu_exclude_users',20,2);
function sq7_radu_exclude_users($qs=false,$object=false){
    //list of users to exclude

    $excluded_user = '1,2,3,4,5,6,7'; //comma separated ids of users whom you want to exclude

    if($object!='members')//hide for members only
        return $qs;
    $args=wp_parse_args($qs);
    //check if we are searching for friends list etc?, do not exclude in this case
    if(!empty($args['user_id'])||!empty($args['search_terms']))
        return $qs;
    if(!empty($args['exclude']))
        $args['exclude']=$args['exclude'].','.$excluded_user;
    else
        $args['exclude']=$excluded_user;
    $qs=build_query($args);
    return $qs;
}