It seems to me that there are several different issues here. I'm trying to put things in order in my mind, so I'm sorry if I'm stating-the-obvious and repeating other people's posts.
First of all, I think it's pretty clear that there was a poster, a Buffista, named Gus. He had a personality, a connection with other people, a history with them. He contributed to the community, asked nothing in return, was liked and respected by people who posted with him. We know for sure that this is true, because we were part of that. We were the ones who interacted with his posts, who used his codes, right?
Then, there were the facts he told about himself. They may be true or may be entirely (or partly) false, I have no idea. But their level of truthfulness has nothing to do with the emotions and conversations that the person behind the name and the stories had with other people on this board, right? I mean, if you laugh at somebody's remark, argue with them on a philosophical point or flirt with them, it's with their font on the screen, not the "biography" facts. So, yeah, it would probably sting to think that a person invented a whole bunch of stories and fooled at least some of us, but that person didn't invent the things we were present for, the personality we got to know, right? So, for me, the truthfulness of all these stories is less important, at the moment.
From catching up here, it seems to me that we know that a person by that name, in Wisconsin, was there. We also know he was a Weremonkey, because that's how we named him. Was he actually bitten by a monkey? I have no idea. And at the moment, it doesn't matter that much to me.
The one thing which I feel is important for me to know whether it's true or not is the report on his death. Regardless of other stories, taking this one at face value may hurt people. Telling a story about that is involving the online personality with the "outside" facts. And that's what makes it different, IMHO, than any other coming-up with stories about a person's life events.
Regardless of all the other questions which came up (PhD or not, for example), but definitely because of the accumulation of them, it seems to me that finding out whether the poster who named himself Gus actually died is the one question which is worth seeking an answer to, at this state of events. At least, that's the one question whose answer would change how I feel personally about things.
[Edit: of course, x-posted with lots of people who said it better and faster while I was typing this.]