That is my description. For the type of tackle he was completing, there isn't really a reason your knee should be anywhere near the player.
I've been casually watching some matches to try and find 3rd man tackles to compare, and firstky, it's quite difficult as many don't attempt the type of tackle he made, but there was one by Daryl Clarke after 4m30 in the game the other day, and his technique was very different. His legs go nowhere near the ball carrier. That's what I mean by unnatural, if you are throwing your shoulder at the ball carrier your knees should be clear really. It wasn't orthodox.