Not Dangerous Play? Really?

I was indifferent as to who was going to win Thursday night's semi-final (yes folks, it's a semi-final game) with the Chicago Fire and the New England Revolution. I'm not asking this because I was upset the Fire didn't win. I simply do not understand how Taylor Twellman can nearly kick a Chicago player in the face and it's not considered dangerous play. Has anyone seen a good rules of the game explanation for this?