Given that Bodhidharma was sent to China to straighten people up, and did some straightening in the first two questions with the Emperor, I'm beginning to think that the third question, "who are you," means simply "who are you to be contradicting my beliefs."
I showed my photos to Henry Holmes Smith every year or so when I was in school. One time he looked at some strange things I was doing and said, "what gives you permission to do these." I mulled over his question for a year, and actually changed what I was doing in my quest to answer his question. The next year I brought new work. I told him that I had pondered his question for a year. He was slightly embarrassed. He said he didn't mean anything by it. BTW, Henry Holmes Smith made photos with Karo Syrup. He was a legendary artist and teacher.