Replay question

I was just watching a replay of the game I just played, and at the 6 minute mark when one of my team mates rage quit, the replay says that everyone concedes and the game ends. WTF? We played a hard fought game with the AI on our team and eventually won, with an incredibly close finish (our citadel fell well below 10k hp before I managed to drive off the Giants for good). It was a great game and I wanted to see it from my allies point of view (he was the man ), but it ends pitifully early instead. What's going on here? Does someone dropping = replay is automatically terminated at that point? Why the hell would that be the case?

Stats for the game in question, in case anyone was interested: here