Ok. What I said was maybe rules need to change for hits like that one, since the way it was executed created a very dangerous situation. Just like the hitter needs to be responsible for not hitting a guy in the head, they should perhaps be responsible for not rotating a guy over their back leg resulting in them coming down backwards head into the ice. The hit was dangerous for the same reason a slew foot is dangerous even if the mechanics differ somewhat.
I also think the camera angle of Wall's video is a bit deceiving, Boucher comes in at an angle, his leg carries through under the player as a result of their respective vectors. There's no sweeping motion, but the result is the players legs come out from beneath him.
I think we've all watched it "15 times" + at this point, we'll likely just have to agree to disagree on what happened, failing a frame by frame analysis.