I smoked once with my uncle when I was 13. Then, when I was 14, he was in rehab and I got suspended. I "borrowed" his hookah for the ten days I was out. Burnt holes in my grandma's carpet.
Yeah, I wouldn't really mind if he smoked shisha. I started smoking in high school, and knew that parents could be stupid. I think it would be fine as long as he didn't smoke all the time.