Hargrave's site comes across like it is THE Offical JKD organization. However, the closest thing to an "Offical" JKD site that I know of is http://www.bruceleefoundation.com
which is run by Linda Lee and Taky. The Foundation does not certify anyone.
For marketing purposes, Concord Moon L.L.P owns "the name, likeness, image, domain names, designs, and trademarks of, or associated with, Bruce Lee."
I don't know anything about Hargrave. He might really be that good. IMHO, the whole certification thing is BS ... it is just a piece of paper that costs $1000+ and a weekend of training or watching videos. How many people fail to get certified after handing over the money?