You arent going to win because you are arguing about the wrong thing
Extended warranty is not equal to factory warranty. The FACTORY warranty would not necessarily be voided by a lift.....you are correct, they need to PROVE it broke something before they can deny coverage. But the OP was talking about his extended warranty.
The EXTENDED warranty is very different. Mag-Moss does not apply, so they dont need to PROVE anything, technically. It will most likely come down to the relationship you have with your dealer....will they go to bat for you or not. Something like a lift/lower is probably a gray area. Something like the cam and lifters wiping is less gray, but either way it will be how your dealer portrays the issue to FCA, since FCA will be the one paying the dealer back.