Mutual Culpability
I've learned a new term in the discussion of this incident...mutual culpabilty, which means that both parties merit blame. The driver should not have walked down a poorly lit track in a black suit, continuing to walk closer and closer towards Stewart's car. Had he not gotten out of the car there would be no one for Stewart to hit. His actions are culpable, that is, worthy of blame.
Stewart is mutually culpable because, for whatever reason, his car breaks loose and fishtails to hit him. We can assume that since the car fishtailed (for whatever reason) Stewart did not have control of his vehicle, thus violating the rules of a yellow caution. He is, therefore mutually culpable. We can assume if he had control like the blue car (and others) and followed the line and the speed he would not have hit the driver.
The question to be answered is the intent of Stewart's actions. I have also watched the video several times, and I need to ask the question "Why would a NASCAR champion and experienced sprint car driver not be able to control his car under a yellow when the other much less experienced racers are able to do so? What caused Stewart's car to break loose?" I too have heard the throttle blip while the camera is on the blue car, and there is no linkage to the throttle blip and Stewart's car fishtailing, although that is the next thing we see.
I bet another video will surface where we will be able to hear the throttle blip and link it directly to the fishtailing of Stewart's car.