Why can't they do something like.. The game flashes a message before you join. "You are about to join a session in progress. Do you wish to enter?" You do that and you show the current scoreboard like u hit select. You show the round they are on and how much time is left. You get 5 seconds to decide. If you don't decide you are put in there. Pretty simple really.
It's amazing how every time you open your mouth you prove you're an idiot! ~Vegeta