I have to speak against the OP on this one. At some point you made the assumption that this kid was going to fix the risky situation that he created. That was clearly a poor assumption on your part. At the same time, this dumb kid probably assumed that you wouldn't be stupid enough to plow into him if he was blocking your road. A poor assumption on his part. Either way, there were two poor assumptions, and if either one hadn't been made, then the accident would have been avoided.
You can't ever expect others to look out for your safety, or even their own for that matter. All you can do is to always expect people to be stupid, and take precautions to make sure you're not involved if something happens. I.E. Look out for yourself, and be frustrated with your own actions if they kept you from avoiding an avoidable incident.
Always blaming things on the 'other guy' is what's tearing this country apart, and waisting money on bringing cases to court that shouldn't ever be considered. Buck up a little and just try and avoid it next time.
-J