1996 Jeep Wagoneer trans fluid into radiator

My sister ( who knows NOTHING about cars ) called me this morning freaking out because she accidentally dped a sizeable amount of transmission fluid directly into the radiator of her and her husbands jeep. I told her as a precaution not to start it and to have it towed to a mechanic to have a chemical flush of the radiator done. Well apparently she does not listen and her husband ( who is employed as a pizza delivery driver in a very busy pizza place ) is driving it all around town right now. What damage ( if any ) is this liable to cause and what should be done to fix it or can it be fixed now that it is all through the engine, water pump and all other mechanics of the jeep?
Thank you, sincerely, the little sister of a pain in the butt