That's the good and bad thing about this forum. The anonymity it provides means that if you disappear it could be because you have died of a heart attack or simply because you have decided to leave the forum without telling anyone or leaving a trace. I venture to think that in most cases it is the latter. I hope someone can reassure the OP that Flying Hellfish simply decided to leave the forum and is doing OK.
Yeah, when someone disappears from forum, you can only try to guess what happened to him. Did he just decided to leave forum without saying goodbye or something bad happened to him. In recent years so many Bitcointalk members from early days disappeared mysteriously and most of them haven't shown any prior signs that they're planning to leave.
But that's how forums works. I guess that in most other forums nobody gives a shit about when some old member disappears.