In all fairness, what Dr. Oz was referring to was a Lancet report claiming that school closures would be responsible for only 2-4% of total deaths (children, parents, teachers, family, and family friends), not 2-4% of children, who go to school. He didn't chose his word very well.
This being said, from what I can tell, the report relies on a best case scenario where the parents all stay at home i.e. the entire children-parents-teachers-family-family friends ecosystem is isolated and observes the stay-at-home rules to a t.
In reality, many parents, teachers, family friends, etc still go out and go to work as part of the so called essential work force, which opens up an entirely different can of worms, making those 2-4% of total deaths a pipe-dream.