First you need some method of confirming that this guy is one of the top 300 cryptography experts in the world, which is highly unlikely. Secondly, I don't believe it takes a top level cryptographer to build bitcoin, it takes a person who has a broad knowledge of many different computer science topics and an ability to conceptualize complex systems in their head. I'm sure that there are tens of thousands of people 38 years of age right now that meet that criteria. The concepts required to build Bitcoin already existed and were simply waiting for someone like Satoshi to bring those ideas together, it was only a matter of time before someone would see how to fit the pieces together.

And as another poster mentioned, the rest of the world besides the US uses British English. For example we use it here in Australia. But if you notice, I use US spelling for some words (look at how I spell conceptualize). Satoshi also used a mix of British and US spelling, so he could essentially be from any English speaking part of the world, even the US. And the fact your guy was familiar with Bitcoin in its early stages isn't surprising if he is a cryptographer, I imagine that the vast majority of cryptographers worth their salt keep up with the latest technological achievements related to their field of work. The evidence you have isn't really any more convincing than the evidence on Dorian Nakamoto.