Curious what you'd be attempting to achieve by spraying greencure right before harvest?
If it's just to prevent further infection, I've never observed it spread once the plant is harvested. Just cut out the moldy buds and set them aside. The rest of the plant will be fine. The strain of mold that grows on living plants is different from the kind that grows on dead plants.
Don't spray anything, this quote is 100 percent correct.
Peace