I believe a good compromise that wouldn't require much effort to implement is to change the kick timer to 30 minutes, and make it/keep it 5 minutes for game-room afk (because such players do not actually contribute to all vs all gamemodes as such gamemodes finish when nobody is ingame, and the game has to be restarted).
however, a role of sorts should be added to players who are gone for more than 10 minutes where, like you say, they give no contribution when are killed, or lose any for that matter.
