I agree with Bill, at 9 he should be able to be mentored properly to operated a scroll saw, with emphasis on safety and building good habits. Teaching young children responsibility is a great thing, and scrolling would be a great addition.
I'm a firm believer that kids should be taught as soon as possible. My son, by the age of 10, has already operated a scroll saw, and other power tools, as well as welding, routine maintenace on his dire bike, etc. Again, with EMPHASIS on SAFETY. If the child is able, start him/her learning to work with their hands.
Good luck!!!