The clutch linkage on the car broke, meaning he could engage the clutch pedal, which is why the car would not go into reverse. When he got the car back to the line it would still roll forward. Watch the video again. He rolls forward into the pre-stage beams while Jason is still trying to make his final adjustments. When Jason was done, he looked and saw that Khalid was already pre-staged and knew he needed to get away from the car. By rule, once the car is pre-staged, the crew are no longer allowed to touch the car. Jason never gave Khalid the okay sign to go in, as is customery for the crew chief to give to the driver. That is why Khalid sat there and never staged. Veteran of the sport as he is, he should have known that once Vangergriff staged he had 7 seconds to go in or he would be timed out. In all truth, it probably didn't matter much because since the clutch pedal was inopperable, the clutch itself would have had way too much heat in it. It most likely would have grabbed as soon as he hit the throttle and blown the tires off, but we will never know.