I'd get in their face about it, and hire a lawyer if needed. I'm not sure what the warranty agreement says, but I'd bet there has to be some leeway in there for failures that happen on the road and the fact that further damage done simply by virtue of the fact that you're using the vehicle for its intended purpose is immaterial for a warranty claim. What if this happened on a busy freeway with no safe shoulder to sit on? What if your light went on and you had to stop in a dangerous spot and a cop told you that you have to move your car? I mean there are so many scenarios that reduce what Mopar told you to a bit of an absurdity.
Warranties are getting worse and worse. I've had multiple issues with my current ram and last ram that dealers just flat out could tell there was something wrong, but weren't interested in spending the time on it so they just told me there was nothing wrong. On each instance I had to run it up the flag pole at ram to ultimately have the issues fixed (and ram completely acknowledge there was a problem), but not after multiple trips to dealerships (5-8 times for the handful of these instances) and a huge waste of my time.