What to do? Dumped horses?

ok so my lil cousin's dad picked up 2 horses that were dumped one is a blind wild mustang the other an aproximate 12-14+ arab/quarterhorse both are mares and by the muscle toning and jus overall appearance and the way they act have not been ridden in a long time. My cousin has about a weeks worth of expierence with horses to my 12yrs and wont listen to my advice. He thinks that he can pay for 2 weeks of training for the arab/qh and just be able to slap a saddle on and ride....but i know that he will probably get hurt if not killed. He has no experience and no background of what the horses were used for.. one probably used as a brood mare! What do i do? i dont want him getting hurt but it seems like the only way for him to learn his lesson is to let him make his own mistakes. Yet it just pisses me off that he wont even work with them himself hes jus going to let someone else do it for him. And for the moment im the one taking care of them on my land with my feed and water, and he wont even be around to work with them! What do i do?!