Actually, rather more like saying "We won't accept another shipment of flowers mixed up with weeds until we sort the weeds from the flowers we already have."
That's not what they said. They said we are not taking flowers/weeds combinations that arrive on purple trucks. But if you want to dump a whole mess of stuff in a red truck, that is fine with us.
Meanwhile, they don't allow the gardeners to weed the garden because the gardeners are not dressed in their sunday best.