My mom used to do this to me to the point where I wouldn't leave the table unless I literally stuffed my face full of things I didn't like, and all that because I was "eating too slow". I still dislike those foods, and I haven't got the healthiest relationship with food or eating, just saying.
I know he has to get his nutrition, but the fact is most of us have been avoiding or hating greens until high school or something, so even though it's a reasonable approach, it's really done nothing for my generation, and me in particular. I do eat healthy now, and I'm a vegetarian, but what's going on in my mind during the endless "don't think about eating"/"EAT TOO MUCH OF EVERYTHING" cycles is not nearly as healthy as my diet, and I'd rather have the capability of intuitive eating instead of what I got.