A pilot friend asked me to demo my drone at the airport where we both have airplanes and hangers. I have my FAA part 107 licenses as well as a PPL. I asked the airport owner if I could do short flight in front of my hanger which is near a closed grass runway. The owner said no problem and said he might want to see it too. While flying the drone, another pilot came over and said that what we were doing was not legal. He had never operated a drone before. After I calmly explained the rules, he left. A few minutes later he came back and said that he looked up the rules for flying near an airport and we were ok. He did not apologize for his attitude. The moral of the story is that we Drone pilots must know the rules and be able to educate pilots when operatizing near an airport.