If it were a soccer play, I would have no problem. People get hurt playing all the time. I played in high school and in college, and I got hurt. But the only way you can possibly think that was not intent is if you didn't really look at what happened. Back to the ball; no attempt to avoid contact; jumping into the contact; arm coming up and through the head. The intent is clear from the behavior.
But I will tell you what would cause me to take my son off the field--if he ever engaged in behavior like this.
But just to be clear--you are okay with soccer being played like #3 on Seneca is "playing," is that right? You'd be okay if this happened to one of your players, yes?