It did too make an impact. The defender was leaning forward and had his momentum going forward, he could have made a play except he was pushed backwards, reversing his momentum. If you push someone away from the path of the ball you'll be called for interference always, and that's the right call always.
Better look again zip, the defender was moving away from the ball, beaten badly by the outside cut.
DJ stuck his arm out, but you can see that it had no impact on the defender. And - I will reiterate - just before that, the defender had grabbed DJ.