I have a few students who ride and they all have been OK. I started on the road when I was 17 too on a cb350 and have done OK.
That being said I think you need time to understand how people act and react in real life. I have seen dozens of students in accidents where they technically didn't do anything wrong, but they didn't see the accident coming like a seasoned driver would so they couldn't avoid it.
Ninja 250 and the new little honda 250 are supposed to be nice and make you ride to go fast instead of just twisting the throttle.
Rider safety course first.
Little update on the purchase
of a bike for my son. I ended up picking up a 1980 honda cx500 for my son. One of his friends has one and he really likes the way it looks. I bought the bike for $300 and we did some work on it: carbs cleaned, new clutch cable, fork seals, tires and new paint that my son picked out. Bike runs great and has more power than I thought it would. Body work done, should be painted tommorrow and if tires show up bike will be finished this weekend. Around $800 total investment and we will do some other changes this winter. Mainly new windshield and probably change handlebars then also, he will have a little money left over for any mods wanted. Thanks guys for all of the input.
If it attracts this kind of crowd you did well!