Intent, which you raise, is in the eye of the beholder. The announcer said it was because he slung him down.
Either way - really bad call and I am not sure how they want to fix it. The old rule for hitting the QB along the sideline used to be if the defensive player stayed in bounds. Now, the QB can just act like he is going out of bounds but continue towards the defender and they get an extra 15 yards.
This is BS. If you are going out of bounds do so or slide early. If not, you should be fair game like any other player.
I need to look again. I thought that was a sack far from the sidelines. I was not saying I agreed with the way the rule is written. It seems that players have found a way to abuse some of them - as you said, and by ducking to put their head in the line of fire. How do you officiate intent? Above my pay grade. But that is what they have left themselves open to.