Update: No rematch. UGC has ruled it close enough.
"Hello again We have decided to keep the score as is. While the demo does show no one on the cart when the round ended, we do believe they pushed it far enough to be captured. There is likely a bug associated with the animation of the cart falling into the pit, which caused the confusion in this match. We have sent your video to Eric Smith of valve, and he said his team will take a look at it. Thank you for bringing this issue to our attention. -Firefly"