What was the motivation for abandoning the Datsun?

With the battery dead there was no way to get the Datsun running. If he hoped to get the car back to a paved road, McCandless had no choice but to walk out and notify the authorities of his predicament. If he went to the rangers, however, they would have some irksome questions for him: Why had he ignored posted regulations and driven down the wash in the first place? Was he aware that the vehicle’s registration had expired two years before and had not been renewed? Did he know that his drivers license had also expired, and the vehicle was uninsured as well?

Truthful responses to these queries were not likely to be well received by the rangers. McCandless could endeavor to explain that he answered to statutes of a higher order—that as a latter-day adherent of Henry David Thoreau, he took as gospel the essay “On the Duty of Civil Disobedience” and thus considered it his moral responsibility to flout the laws of the state. It was improbable, however, that deputies of the federal government would share his point of view. There would be thickets of red tape to negotiate and fines to pay. His parents would no doubt be contacted. But there was a way to avoid such aggravation: He could simply abandon the Datsun and resume his odyssey on foot. And that’s what he decided to do.

Instead of feeling distraught over this turn of events, moreover, McCandless was exhilarated: He saw the flash flood as an opportunity to shed unnecessary baggage. He concealed the car as best he could beneath a brown tarp, stripped it of its Virginia plates, and hid them. He buried his Winchester deer-hunting rifle and a few other possessions that he might one day want to recover. Then, in a gesture that would have done both Thoreau and Tolstoy proud, he arranged all his paper currency in a pile on the sand—a pathetic little stack of ones and fives and twenties—and put a match to it. One hundred twenty-three dollars in legal tender was promptly reduced to ash and smoke.

What type of rhetorical appeal does the author use in this passage?