If the cause was a coolant leak then Ford would pay. If the cause was the oil failed, he did not follow the warranty instructions of the oil, so his oil warranty would be denied.
Agreed if a coolant leak was at fault Ford would pay, how could someone blame the oil?
Now if his Amsoil dealer sold him an extended drain oil and neglected to inform him about problems with his engine and extending drain intervals what happens? Amsoil won't pay, Ford won't pay, does he visit a court house with the rep for giving bad advise if the oil did in fact cause the failure? Lots of bad info is exchanged by misinformed or over eager sales people! It happens everyday.