The approach angle is all aerodynamics in regard to a flapless landing. No flap = less drag which will shallow out your approach path. It is plain simple. Particularly for a PPL student. Divergence from the stated will increase risk. Fine if you are a 20,000 hour ATPL, NOT if you are a 20 hour PPL student. If he landed before the displaced threshold then I would agree with your statement in regards to responsibility as he would have failed in that respect. If he landed past it, then there was nothing wrong with his actions. Now why there was a car crossing in front of an aircraft on approach, with the right of way, that is the pertinent question.