I don't know, blaming Tony Stewart for this makes little sense, the other driver unfortunately took a huge risk, you don't walk on a track if you can avoid, it was a night race, he was wearing black overalls, the visibility is limited inside the cars..
also for people talking about throttle noises, it's hard to know because there are multiple cars on the track, but these cars are heavily sensitive to throttle inputs I think, and they use throttle to control and steer the car, also unfortunately when the driver went under his car and tires it probably affected the revs, and Stewart could be having a panic reaction, I really don't see a reason or the historic in Tony Stewart to do something like this on purpose, and I see the attitude of the other driver as extremely unsafe,