Holy ****, it really has disappeared. WTF?
If there was a problem, why not just moderate whichever offending posts caused the problem?
In general there are two reasons why a whole thread might disappear.
1: It's got so many posts that need editing that it's going to be much easier to remove the whole thread.
2: The basic thread itself is against the rules, or not deemed suitable for the forum.
The thread in question opened with a fairly gory picture, which I suspect is the reason it was removed.
We don't leave notes about why a thread was removed because it would be rather time consuming to inform everyone who had a post/thread removed every time via email, and it's not practical via the forum (to my knowledge).
The forum software as standard lets us leave a reason for a threads removal, but it's only visible to mods AFAIK (and a lot of the time leaving the title visible to users would partially defeat the reason for removing a thread).