He could have walked from his car to trailhead, turned around and walked back to car and maybe was picked up by another driver- maybe to go on a nearby run- maybe a slightly different route but that would end up back at Moller Staging Area where Philip's car was left by Philip?
This is the kind of scenario I was entertaining. I had not thought of another run. I have read through accounts of people who have recently gone out and ran the route PK planned, and learned the lot he was in is very small.