I believe you are talking about the Quinns RC while Ted is referring to the Pats RC.Gotcha.
From my pov the tackled player was fairly upright - it appeared like the tackler knew the ball was gone and stood up in contact without grasping, which caused the past-horizontal due to momentum. He could have stayed low and grasped the player and maybe got a different outcome.
I think the arm going out to the ground first marks the danger of the angle. Could easily break your collarbone trying to take all your weight like that as well. That's why driving a player is as bad as dropping a player sometimes.