The source for one version of LOIC can be found on GitHub:

https://github.com/NewEraCracker/LOIC/

A quick skim-read of the code mentioned in the post shows that this version seems to be different, specifically:

https://github.com/NewEraCracker/LOIC/blob/master/HTTPFloode...

  if (random == true)
    buf = System.Text.Encoding.ASCII.GetBytes(
           String.Format("GET {0}{1} HTTP/1.1{2}Host: {3}{2}{2}{2}",
             Subsite, new Functions().RandomString(), Environment.NewLine, Host));
  else
    buf = System.Text.Encoding.ASCII.GetBytes(
           String.Format("GET {0} HTTP/1.1{1}Host: {2}{1}{1}{1}",
             Subsite, Environment.NewLine, Host));

(botched indentation is my own)

The Host header mentioned in the blog post is present, the protocol is now HTTP/1.1 and random string appears to be an attempt to defeat a simple packet matching algorithm.

I doubt many legitimate requests these days come without a User-Agent header, though...