They’re saying that not prioritising (disbelieving) GPS data is bad, hence there’s no excuse for it

So that’s the same thing you’re saying

Yes, I know. And saying that as a rebuttal to a comment where I’d said the same. Hence my reply ;)

The technology should be resilient against GPS spoofing. If it “knows” it never left the mountain road, it’s not crazy to design it to reject an anomalous GPS signal, which might be wrong or tampered with.

I think the likelihood of that happening is significantly less than the likelihood that a car took a new road or other path not show in the cars mapping data.