Dirty, and now dangerous?

This is a potential issue for any ICE car, including hybrids.
I recall some owner's manuals having warnings about parking over dry grass.

 

""I don't know if cars explode these days, but it didn't. It just went up in flames," he said."

Is this an advantage of diesel over gasoline? A lower propensity to explode?

 

Gasoline does have a much lower flash point than diesel. You can light a puddle of it outside, during an Alaskan winter, and Death Valley may not be hot enough during the summer to make a puddle of diesel ignitable.
Flash point - Wikipedia
"The flash point is a descriptive characteristic that is used to distinguish between flammable fuels, such as petrol (gasoline in the US), and combustible fuels, such as diesel."

 

Hot tailpipe + dry grass = Roasting ICE over an open flame.

Now, let's direct our attention back to that one Tesla that caught fire instead....

 

When cats became prevalent in 1975, they were telling people not to park on grass.