I agree that Draymond's arm got stuck, but I don't see him making any effort to remove his arm before plowing through.

To me, it looked like Dray was pushing Mills out of the way and ended up with his arm hooked around Mills' neck. A kind and gentle person, seeing that they were about to smack someone in the throat, would stop and get their arm off the windpipe of their fellow human. A person who was super competitive and trying hard to win would, at least, make an effort to move their arm back and down while running past. In this video, we see the third option: a stiff arm clothesline across the neck.