I generally don't get involved with flag disputes. Usually it is better if people work things out between themselves. Nobody is required to explain their reasons for flagging, and he is no exception. If you want to get ahold of him, email is the best option. I may be mistaken, but if I am judging the tone of your comment correctly, it probably won't be a productive conversation. Again I could be wrong here, but I get the impression that you are more interested in making a point about how you were wronged, or he is abusing his power, than just getting an explanation for why you were flagged.