Will be interesting to see what the consequences of Ben being unliscensed (and unhelmeted) have on how the judicial system deals with the accident. For the lawyers out there, does it make any difference if the lady is at fault, but she hits a guy who wasn't legally on the bike?
I wrote about this on another board a couple weeks ago in the context of a squid doing a get off with a scantily clad girl on the back -- on the issue of her relative fault in getting on that way, and the relevance of how much she knew about motorcycles and gear if squid rider never said shit to her when he picked her up to go for a ride.
But to answer your question: yeah, it probably will make a difference in a civil case, or it sure would in California and most jurisdictions. Assuming facts that we don't know for sure, I'll say that she'll likely be liable for having caused the accident. BUT . . . and here's where it's relevant . . . his own negligence in failing to take reasonable precautions to minimize injury from reasonably foreseeable accidents could limit the amount of damages recovered. It's just like the seat belt defense, which goes like this: Sure, I was in your lane when I hit you, but if you'd been wearing your seatbelt, your injuries would have been far less severe (and I'm liable for those), but not for all that plastic surgery and neuro surgery that resulted from putting your face through the windshield. So, if the defense lawyer hired by her insurer convinces the jury of something like that, then Ben would have lower damages awarded and get less money from her insurer.
Keep in mind that if his medical insurer had paid for his face surgery, there's a good chance that they would have a lien against his eventual recovery, whether by judgment or settlement. It's complicated how that gets apportioned, but broad brush: the less he gets from her for his own negligent contribution to his injuries, the less his med. insurer gets back. Often, a lot of this is about which insurer pays how much, though it's typically improper to so much as mention insurance in the trial, so most jurors see it as just between the litigants (and sometimes it is, whether in whole (as in no ins.) or in part (as in judgment above policy limits).