Lord. Everything here is wrong.
For starters, the injury doesn't happen because the defender pulls Pollard down while holding his waist.
The injury happens because the defender purposely uses his body, specifically his hip/butt, to sit on the runners legs. You can literally play the video and see this at :1 sec. Again, your momentum when making a tackle from the side does not allow your legs to go UNDER they go around. In other words, the tackle ends up being a rolling twist.
Secondly, it's not unintentional when the point, like the horse collar tackle, is to land back on the runners legs. That's literally the point of this type of tackle.
I don't get what's arguable here. When have you ever made a tackle and swung your legs under you accidentally??? It's why all the LT videos where he's moshing dudes from the side you see his legs swing wildly with disregard. This is not a regular side tackle where the runner and tackler continue to go sideways and then the tackler lands on his hip. The defender CLEARLY swings his left leg under his body to create momentum backward and land on Pollards legs to stop him from moving.
You can say he didn't mean to hurt him. But that's the same thing that was said about the horse collar tackle.
I played, plenty of the niner brehs know I played. I've made plenty of tackles like that exactly like he did. He ain't no contortionist that's able to twist his body in all kinds of ways. He simply made a textbook back angle tackle. You wrap up no matter the angle, any other way is a broken tackle or a sled ride.