Call me overly cautious, but I wouldn't ride with a friend who is 30,40 or 50 if I knew that person was uninsured. I also do not care if they are former motorcycle racers and fabulous riders. Say a deer jumps out, and the uninsured rider takes you down. Your insurance company may not accept the bill and leave you to fight it out in court (we all know who wins in this scenerio, Lawyers). If your insurance company doesn't want to pay and decides to duke it out in court on your behalf, you still have to wait a long time for a settlement (without a bike). Yeah, I know this is "worst case scenerio" thinking but it's that kind of thinking that has kept me safely riding for 40 years when everyone else (who are even more cautious than I) think I have a death wish for riding in the first place.
As far as parenting, Beav said it best.