Ummm, call me ignorant, but unless that guy did some serious ass kissing and apologising, there'd be a conversation/ass beating going on out of sight from the kids. I'm laid back, but if you want to see me lose it, mess with my little girl.
Props to you for spending the time on a project with your kids. You can't win them all, and there was probably a better lesson in there for her. It's about the time spent, and before you know it, she'll be working on her own autocross car!