In the article, the boy did this rather than eating junk food. Sounds like junk food would have been healthier.
Maybe the key point of the article is that anything should be taken in moderation -- too much of anything can be bad.
I have known women who want to stay thin that eat a can of tuna a day -- especially when trying to bulk up (distance runners, etc).
One of my friends, a poor grad student, was eating canned tuna because she had no money. She ended up with some memory loss and nerve damage in her fingers.
With a stack of Chicken of the Sea from Sam's Club in my own closet, I was naturally concerned when she told me of her recent diagnosis of mercury poisoning, but she told me she had bought the cheap, no name tuna, so I feel a little better.