As someone that played hockey, if you miss a check you go onto your knees and then step up again. This guy was aiming for Johnson. If you see a clearer vid, he actually shoves his skate hard when he first makes contact.
Did something happen between the two earlier in the game that he'd try to get a little 'payback' for?
Unfortunately, the videos I can find are clearer than the gif I created, but still aren't that clear.