There are lots of intentional fouls that don't get called as flagrant. Like at the end of a game when teams are fouling to stop the clock. Rarely is the ball touched, and almost never are they trying to touch it. In this case because he was "thrown" to the ground and it wasn't a play on the ball, they called it flagrant. Had he just kept him from shooting but he stayed on his feet, I doubt they would have called it.