It seems to me that you’re looking at the HttpWebResponse object and not the string from the response stream. Check it out.
By the way, the tutorial has a quite a few problems - make sure you improve the code before using it for anything real. For example, Close() methods won’t be called if an exception is thrown in or after GetResponseStream() and you’ll get a null reference exception if GetResponse() fails.
If I was you, I would add a C# project to AOT and handle it there, because I wouldn’t have to use fully-qualified names (leading to better readability), I would be able to use using blocks to deal with disposable objects and so on.