Its a bit naive to think the forum community could have any significant impact on UT3's success, or lack thereof.
It is a well known fact that the vast majority of gamers never set foot on gaming forums, its is estimated that, for any given game, only around 10% will ever set foot on the official forums (and even less will actively participate), and much less on thouse belonging to fansites, and thus, even if the forum community is so horrible, vile and evil that they could effectively make everyone who reads the forum choose not to buy the game, we're only talking about 10% of prospective buyers here, and that is just not going to sink any game, bad reviews will actually do more harm, but even thouse are not enough to sink a game.
Alot of people actually have bought UT3 for the PC, im sure you guys can easilly find the numbers, and even if we filter out 50% of them (since Epic calculates that 50% of UT players are purely offline players), the remaining 50% of all thouse who bought the game are clearly not playing it online, one look at your server browser will make that painfully obvious.. so the reason people are not playing online is not that we have scared them from buying it, it is that for whatever reason they do not want to play it, or cannot.