This is completely unfair comparison. Deriving is not comparable to reciting/applying something... Dijkstra's is pretty intuitive once you know it and about 10 or 12 line of python code? Quantum mechanics took years and multiple geniuses to figure out yet somehow undergrads and graduate students are able to learn it in one or two semesters.
I'm not sure I follow - interview questions are supposed to be about deriving things, not reciting/applying them. In any case I'm pretty sure he was being sarcastic. You aren't hiring Dijkstra.
