Warning: Tiny little kid on a ginormous horse.
I wouldn't have a problem with this at all if the kid had boots and a helmet, they were in an enclosed area with no loose horses, the Belgian had a halter and lead rope on, and the kid had at least one adult holding on to him.
But nooo. The horse is loose out in the pasture with no one holding on to him, and the kid is sitting there bareback with no helmet or boots. Plus the loose horses, particularly the foal and what looks like a yearling. It only takes once for a seemingly dead broke horse to spook and end up mangling somebody. I don't care how quiet he is, and I understand that he is a draft. He looks like a real sweetheart, but he's still a 1900 pound prey animal with big, sharp hoofies the size of hub caps. He may be as close to bombproof as horses come, but I guarantee you that all the other horses there are not. If one spooks, they all spook, including the one that your kid is sitting on.
Do they think that horse is just a big puppy? These people need a reality check. That animal is the equivalent of a frieght train with a mind of its own and is more than capable of killing a human, especially a child with no safety gear. Sure, 99 out of 100 times, nothing happens. But it is possible, and it does happen. What are you planning to do when your luck runs out? There's sure as hell nothing you can do if and when that horse spooks while your kid is on him. And that's a long way for anyone to fall. Then you have those feet to worry about.
Lord have mercy.