Stewart was spraying the guy. It is done a lot and this time he got a bit to close or the guy lunged. Stewart was going to spray the guy with dirt. I have seen it done thousands of times. I have been guilty of doing it during CrossCountry MX races 30 years ago, it is known situation, you battle with a guy, he goes down, he gets mad, he stays on the course and you spray him with dirt. Tony Stewart was spraying the guy with dirt debris. Then he either comes at you in the pits after the race and the fight is on. Or he calms down and shakes it off as "just racing". I feel bad for the sport, I feel bad for both sides of the Familys involved. Anger got them both in trouble.
I have been guilty of both sides of what happened. To the point that a back tire on a dirt bike ripped up my riding pants and tore the buckles off my racing boots. I look back and it was all silliness, but hey, it is what it is when your in the heat of things.
I think this is on the right track. Spraying of dirt, yep. Been there, done that and got the T shirt.