Well, 600 fps is gross negligence and it is only a matter of time before someone is hurt and the owner of the field is sued under tort law. On the other hand this young man might just end up in jail facing criminal charges. However, that is not the worse thing that could happen someone could become seriously injured and even disabled. I just hope that those unfortunate enough to play with him wear eye protection that can stand up to that high velocity.
One more reason for the world at large to ban airsoft...keep giving them more and soon we'll be using squirt guns.