Depends on the kid really and how interested the parents are.
I have a 12 year old nephew who's had a Corn for a couple of years. He's a pretty laid back child and takes caring for it seriously. He's calm when he handles it and doesn't take it out to "show off" to his mates unless there's an adult present. He has a lot of support from my bro and sis-in-law who've made efforts to find out about caring for the snake. They make sure that he does what's necessary and he's reliant on them to drive him to the reptile shop for food and substrate.
My other nephew, I wouldn't trust with a stuffed toy!
The parents also need to understand that a) Corns live for 15+ years and b) a child's attention span can be slightly less than this! Not to mention that the child might want to go to college in a few years and are unlikely to take the snake with them (although I know there are a few folks here who have managed it). Make sure the parents are on board with the idea - there's a chance that they will ultimately be left with the responsibility of caring for the snake or rehoming it.
A bite is never pleasant but with a Corn it's more the surprise of it than any actual damage. They have tiny teeth - I think I've seen it described as like being "pinched by angry velcro"! A bite happens very fast and until you "tune in" to their body language, you might not see it coming. However it's unlikely that a Corn will bite once it settles in. If you buy something slightly older than a hatchling, there's a greater chance that it will already be accustomed to humans and will be less inclined to be flighty.