T.N.
Hi L.,
May I recommend, having studies martial arts, that you enroll him in Aikido vs. Karate or Tae Kwon Do. You might also consider Tai Chi. I cannot recommend certain instructors, but I would definately stay with those two disciplines. You might also take him to the free classes, like the introductory class, and interview the instructors and find the best fit for your son.
Best of luck!
T. Nelson