After going over the facts with HL2 Fallout´s Mr Bond, we have come to the conclusion that this is most likely a hoax. We are still waiting for final direct confirmation from Valve. What we do now is that the IP used to make the post does not match any previous IPs Gabe Newell has used, nor does it match his ISP, or Valve Software´s. The IP´s host is also running open proxy services, which means it is accessible to anyone.
Ceux qui ont un bon niveau d´anglais comprendront, d´ailleurs, désolé, mais j´ai pas envie de traduire.