I've put both my kids in front of me while riding snowmobiles and let them take the controls many times, and we had reached speeds over 70 MPH. The kids rode with me from the time they were 3-4 Y/O. They had their own snowmobiles when they were 5 years old. They were both about the same age as that kid. Granted we were blasting across 600 acre fields in full riding gear. They also steered my truck down the dirt roads! When they could reach the pedals too, they had full control I never felt they were in danger because They were taught before hand.
Like Bob said, the kid may have been riding a few years already. I do not condone that the father did not insist on AGAT for the kid, just in case.
And to prove I'm a really bad parent, they were both learning gun safety and to shoot rifles at the ripe old age of 5. They both lived through it and are now able to out shoot me ! To teach them the power of a firearm, the first time they went to the range, I took one of their stuffed animals and put it down range, the first shot vaporized the toy , I turned , looked at them and said, THAT's what it will do to a person. As you can imagine, it left a lasting memory and respect for firearms.