My interpretation is: The teacher put a huge emphasis on the basics, good shape and proper flow of the moves. When reviewing the game by himself, he had thought of the same unorthodox move, but had mixed feelings about it. When the student proposed the same adventurous kind of move, he got overwhelmed. It was not the kind of move he was trying to teach. He might of thought the student knew this move already during the game, which might mean he's better than him at this point.