Unnecessary call to user_is_anonymous()?

/**
 * Implements hook_node_page_alter().
 */
function redis_ssi_page_alter(&$build) {
  // If the user is anonymous...
  if (user_is_anonymous()) {
    // ... and the generating agent then set the cache.
    if (redis_ssi_generate()) {

However:

function redis_ssi_generate() {
  return user_is_anonymous() && !empty($_SERVER['HTTP_USER_AGENT']) && $_SERVER['HTTP_USER_AGENT'] == REDIS_SSI_USER_AGENT;
}