Except the alchemists weren't practicing nuclear physicists, nor did they actually ever turn lead into gold through nuclear fission, nor would anything in their philosophy have led to doing so, either in theory or practice.

Just because it happens to be physically possible to turn lead into gold using a model that alchemists would never have even comprehended (as their principles were based on hermeticism and religion, not experimental science) doesn't mean they weren't quacks, or that they were half right. They were quacks, and it's OK to see them as such.