Unfortunately you cannot download the source code, the link is disabled. And the GPL license he says he is using requires that the source code must be available for download without any restrictions like "send me an email" or "create an acount".
Doesn't the GPL only require you to release the code if you publicly release the software binaries? I was under the impression that if you only released the results (aka his research and papers) you aren't required to make the source open.