Is this an appropriate place for a father with his 9 yr old son to go and learn trail riding on dirt bikes?

I agree with both answers in terms of it being better to learn on a non-event weekend but with that being said they're still has plenty of room to learn even if you go on a weekend that happens to be an event because in all honesty, not only do you need to learn to ride but you need to learn to ride with others around

Yes on non event weekends of course. Plenty of room for learning to trail ride and explore, for sure. Happy riding!!

Yes, but I would highly recommend doing it on a non-event weekend so it's less crowded. But there is plenty of room with mud and trails to explore!