Sounds like the guy is pretty well aquainted with teaching aikido. There are also people mentioned in the description that you could possibly contact to ask about his teaching credentials. But above all else, go and check out his class.
Rank is rarely an adequate indicator of teaching ability and is certainly no indicator that this man can teach you, personally, something. My teachers are 'only' nidan, but they can speak in languages i can understand (namely, pain and raw physical power). Another huge factor is the type of people you are going to be training with. To say that a teacher is the only one you learn from is pretty silly. A less than inspirational teacher (or even qualified) can be made up with a positive and hardworking group of people to train with.