I did karate for about a year, Wado Ryu style, Sensai was a guy called Steve Rawson, a serving police officer. Steve taught all ages, including a close friend’s two daughters, from around ten. He got the eldest, Marie, up to Brown, and she entered competitions at national level. He had the Japanese Sensai who was the top man as Godfather to his kids.
I give all this preamble to show there are Sensai who run top-notch schools, who care deeply about teaching properly and with respect all who go to learn, and those in turn learn to respect his skills as Sensai.
It might be better if perhaps you found a softer style for your youngster to start with, Like T’ai Chi. For a youngster, it’s slower, not aggressive, but it is a martial art, in slow-motion. It would help him develop his balance and confidence, and then he could move up to the harder fighting styles, like Wing Chun, or Tai Kwan Do.
This man is a disgrace, he shames everything that martial arts are all about, and he should be stopped from teaching as soon as possible.