I'v found corns to initially be quite skittish and they can bolt if they are nervous, because they are so small they could either be dropped or crushed by a small, enthusiastic child.

You would have to give constant supervision while the child was handling it and shouldn't leave it up to them to remember to clean and feed the animal.

I personally would not recomend a snake for a child of that age unless the parents were prepared to have a very active role in its care and handling.

My siblings are 11 and 13 and i would be reluctant to let them hold my corn while i was stood with them, never mind while i was out of the room.