Digl's right.. it's been established that anybody who knows how can modify their registry and play some other game (like Quake3) and make it appear that they are "playing" in the JK2 rooms.
The game is not released yet anywhere, so the only people who could be playing are the developers themselves. If they were doing tests with the Zone I could see that, but I figure they'd do such tests in private (and the Zone has never been known for having "secure" software anyway).
The unique keyserver prevents people from just using a leaked warez copy to play online with (as it did with Q3 and other games). So they aren't pirates. They're just people trying to show off and make others jealous, when in reality they don't have the game either. ; p