This line of reasoning makes littke sense. The fact that certain things were incorrectly labeled as harmless should definitely inform how we go about determining id something is harmful. But the leap that we should expect harmless-seeming things to be harmful is unhelpful.

It's not far removed from flatearthers/qanon/911-truthers/moonhoax people defending theie stance by naming conspiracies thought false at the time but later revealed as true. Such events, and your speculations, are merely examples of the fact that we're sometimes wrong. Not that we should live our lives expecting that every accepted fact is wrong.