I read that. The whole article is ignorant so I do not assume that statement is accurate. Call it the Gell-Mann effect.
Define ‘treatment”. We know how to destroy the entire population of screwworms over a period of years. We know how to clean a wound. You need to put a tiny amount of insecticide in to kill microscopic larvae in a gel to keep out more flies.
Define “approved”. Probably the disapprovers are the people who won’t let you treat a suffering cow who hasn’t lost her afterbirth with a small injection of DES because some fool at a feedlot fed it every day to every single animal, and can’t treat a single sick suffering from a bacterial infection with a small injection of antibiotic for the same reason.
We knew how to clean a wound and apply a gelly like medicine containing insecticide. But probably a lot of what used to work is frowned on today. It takes a genuine ahole to not allow treatment of individual suffering animals.