I didn’t interpret it that way.
There was a closed solid door with a glass storm door on the outside. Looked to me like the kid took a step forward when the man opened the solid door because the man appeared in the video right after the kid started running.
I apologize. I take it back. The video with that article was edited.
I found the whole video. He did knock & step back a couple of times.
https://twitter.com/twitter/statuses/1050186925716443137