First off, the form was made in April 2006, founded by a private individual, who wasn't any of us here presently.
It was known, apparently, that Bully was going to be released that year, so getting the jump on things was not out of the ordinary.
Second, there have been other Bully Forums, but this one has been the longest-lasting, 9 years now. There is quite probably more content posted here than all those other forums combined times two (or three or more). That is pretty good for a game without a sequel of any kind from so long ago.