My 13 yo son wants to take and compete in a martial art. He wants Judo, BJJ or Muay Thai. I am ignorant on the subject, but it seems to me, his physique would suggest that grappling is not for him. He is 5' 10" and weighs less than 120. Long and lanky, it seems to me, is not good for BJJ and perhaps even Judo. Should I steer him towards Muay Thai? This is for sport.