<?php
  require_once($_SERVER['DOCUMENT_ROOT']."/src/simple_html_dom.php");
  $data = $_GET;

  $user = $data['user'];
  $path = 'https://twitter.com/'.$user;

  $html = file_get_html($path);

  $posts = $html->find('li p.tweet-text');

  echo $posts->outertext; //выводит пустоту

?>

foreach( $posts as $item){
    echo $item->outertext;
}