To be fair, he kinda contradicts himself so it is technically wrong. He said yes, Quinton is correct that there must be 7 family members, and then he goes on to explain exactly how there could be more than 7 since not everybody always has 2 legs.
You could say "Hes correct because people have 2 legs so 14/2=7" or you could say "He could be incorrect because some people don't have 2 legs so it could be more than 7 people" Either answer would work, but combining them both would not.
I'm pretty sure this kid is somewhere between 3rd and 6th grade. Kids that old generally don't get that technical and they were most likely trying to support the website more than wording it correctly...
You could say "Hes correct because people have 2 legs so 14/2=7" or you could say "He could be incorrect because some people don't have 2 legs so it could be more than 7 people" Either answer would work, but combining them both would not.