When a player leaves a game they have to be ejected.

Yeah, and sometimes everybody else has to be ejected too.  If you get some jerk who disconnects on purpose, it's pretty much a forgone conclusion that the game is over.

This is not always the case though.  I've been having problems with the game stop responding at about the point that the game is about to do the actual launch.  It won't come back so I physically have to ctrl alt del to get out of the game.  I wouldn't say it's "some jerk" but as the game still being in beta and not exactly "polished" yet, they may be having problems such as myself.  It happens in Beta's.