The sticky part of evaluating negligence seems to be in determining the reasonableness of the defendant's actions. In that respect, judges and lawyers may not be necessarily qualified to make that determination, and so it would behoove the defendant to bring forth a panel of experts to witness on his behalf, so as to set the proper context of the actions leading up to the incident.

Ultimately, the court is trying to determine if the defendant's actions were a proximal cause of any injury or loss, and to what extent such cause contributed to the loss or injury. In this kid's case, based on what has been published, it is pretty clearly established that his actions led to his need for rescue, and that such actions were not reasonable, but he did a lot to mitigate the results so that the burden of rescue was diminished. Based on that, they'll probably settle out of court for a small fraction of the original fine, assuming he shows penitence and not indifference.