Did you read the article?
He claimed that a reliance on junk food can lead to lack of energy and a struggle to focus in young people.
True.
”And then we're taught this is what kids eat, kids need these snacks in their lunchbox, this is what they have for dinner. […] So, we're kind of being confused and led down this path that adults have adult food and kids have kids menus and kids food.
And that's the issue we've got because people are cooking less than ever and relying on these processed foods and it's a shame because kids are getting their energy sucked out of them.
”They're struggling at school with focus, they're gaining weight, and probably having really low energy crashes because these foods are just not going to give your children the energy they need to sustain a healthy day — a balanced level of energy.”
All of that is also true. He’s not claiming ADHD doesn’t exist or that it’s caused by junk food. He’s saying his own behaviour when young was caused or exacerbated by a poor diet and I think suggests he’d have diagnosed with ND if he was young now.