I think it is a hoax. Why post the date and the wrong date at that. Its like it was deliberate. And if my son was found dead, the last thing I would think about is posting on a website. I would probably do it later after the shock wore off but not so soon. Its just the last thing a person would think about. I may be wrong. I hope my hunch is right.
I don't know what to think. First it seemed like a hoax, but the fact that at least one mod there said s/he talked to this guy's mom on the phone makes it seem like it's not a hoax. Unless the mod was tricked too, I guess. The whole thing is very strange.