A single shot teaches the youngster to learn to make the first shot count. An important lesson for someone who wants to hunt. Good way to learn about controlling breathing and squeezing the trigger. Teach the kid that it is about accuracy, and not about how fast you can shoot.
They mention Super Colibri primer-only ammo, but I would be concerned about a novice using that in a rifle and not checking for a bullet exit on every round. It may not exit a long barrel rifle. Aguila states to not use the ammo in rifles, but if you use a short barrel rifle and check that the bullet exits, it is OK.
Nothing about a 10/22 teaches bad marksmanship. Its the teacher and the shooter.