He's clearly not defending himself. And, it's alarming how long she's unconscious. She is hit by him, but it looks like she also hit the hand rail really hard. He basically punched her into the wall. How many MMA matches have we seen where professional athletes are getting knocked out from a blow to the head. They're usually out for seconds. She's laying completely unresponsive for a LONG time as he waits for the elevator to open on a floor and he drags her out and drops her.
That's gruesome. That dude needs to be in jail for a long time, in my opinion.