"So if a 2008 Escalade hits my 1995 Toyota Celica, the driver of the Escalade should not be held accountable? Am I SOL because I drive a POS?"
Irrelevant. If your POS falls apart after running over a 'possum, then you should be cited for operation of an unsafe vehicle on public roads.
You are correct. If the guy was driving an unsafe vehicle then I would say the responsibility is a push.
The description of POS was based on the age of the car in the story. There was no other evidence of the car being a POS. My POS 1995 Celica is in pristine condition but I think that if I were the driver in the story my car would be referred to as a POS based on the age of the car.