I re-watched the relevant parts of episodes 7 & 8, and, even with the penalties, Michael & Kevin would have beat out Chad & Stephanie if Michael wasn't so bad at the roadblock.
Brook & Claire's scheduled departure time for episode 8 was 1:28 AM.
Chad & Stephanie's scheduled departure time for episode 8 was 2:45 AM.
Since Michael & Kevin were at the roadblock before Brook & Claire, and Brook & Claire finished 77 minutes before Chad & Stephanie, and taking into account the extra 30-minute penalty, Michael & Kevin had a cushion of 47 minutes to finish the roadblock and check-in in order to beat Chad & Stephanie for the final spot.
Michael completely sunk their team at the roadblock.