if you don’t think he’s old enough to understand and follow traffic laws? Link
Just pay the ticket, be glad your son is still living, and TEACH HIM HOW TO SAFELY RIDE A BIKE!!! This means MAKING him wear a helmet, by setting a penalty if he doesn’t do so, and teaching him how to cross streets etc. If he’s not able to judge distance, or understand that he has to obey stop signs, then DON’T LET HIM RIDE!!! At least, not until he’s able to be safe. The laws are in place to keep bicyclists, and other vehicle operators safe.