Two weekends ago my 6yo competed in a young handlers class at a show. The judge approached her and began to ask her numerous questions about the horse... and some she got wrong - end of the day she is six, that boy is eight. God knows what answers we came up with at their age. Just because my daughter has a pony and competes, doesn't mean she can or will know everything there is to know at such a young age.
Give the lad a chance. He is blessed to have as much as he does, but he's a child who is learning... chances are he will be pretty darned good and knowledgeable in time when he should know about these, not right know when he is probably happiest when out having fun.