Read all of their findings. They recommend not throwing c/b until 14(puberty) many times on their site and in their presentation.
The study they did was very small. It showed that more stress was on the arm when you had a hard thrower. Over 80 mph. Read all of what they publish and say. Then make your own decision. It is NOT black and white that c/b are better for your arm.
Why risk it? Do you need to lead the league in strike outs at age 10? Excuse me, does your kid need to? Studies change over time but c/b's hurt MY elbow when I throw batting practice and that is all I need to know.
Read all of the information available then make your own decision. Then ask yourself this question, Is it worth the risk of tearing up your son's arm to get a few extra strikeouts based on an incomplete, small study? Cut down your kids pitching duties if you do nothing else. That is a given.