Typically they try to deny all extended warranty claims. Especially the ones that are expensive. Even if it is covered they hope you will just go away and pay it yourself. How can anyone assume that the thermostat just went bad without overheating the engine and giving you some type of overtemp indication.
I once had a thermostat stick shut on a 90 degree day in Florida and it never caused my radiator to leak.
If that thermostat was bad and you kept driving you would loose a head gasket way before it would rupture a radiator with a fan blowing across it.
Most extended warrantys are a waist of money
2019 Horizon 42Q Maxum Chassis w/tag
Cummins L-9 450 HP / Allison 3000
2006 Jeep TJ and 2011 Chevy Traverse Tows