You seem focused on the kids infractions and are forgetting that letting him commit those infractions, actually encouraging him to commit those infractions, is in deed a crime by the parents. It isn't a minor traffic violation. It's called child endangerment and they could get locked up for anywhere from 1-20 years for it.
"Child endangerment is a criminal offense that involves the subjection of minor children to inappropriate or dangerous situations. The purpose of child endangerment laws is to keep children from witnessing illegal activity, and to protect them from situations in which they might get hurt."
The what ifs and speculation of what might happen only accentuate what is/did happen. Not only did the kid break several laws, but the parents not only allowed it to happen, they were the instigators. You can not possibly argue that riding a motorcycle on a 500 mile trip without a license or insurance, and in his case, on a bike with more than double the allowable cc's permitted for a kid of his age is somehow not illegal or a situation where he can't get hurt. It is illegal and he could get hurt and the parents are guilty of child endangerment. Add to it that if they do get pulled over and cited, the kid won't be able to get his license till he's a lot older, they can kiss their insurance good bye, will only qualify for high risk, will get at least fined, maybe locked up, probably have to attend parenting classes, and probably will have their bikes confiscated. The kid might not face a felony, but the parents sure as heck care unless you consider something with a potential 20 year sentence a minor traffic violation.