Author of the article gives one TedX talk, then goes on to proclaim that he's an "expert" at public speaking and ranks himself in the "90" percentile for public speaking. What a joke!
Fear of public speaking is consistently ranked the #1 fear of the average person. I would absolutely put someone who can do it confidently in the top 10%. That's the point of the article: "A bit of work can quickly get you to the top 10%".
Probably over half the population actively dislikes public speaking, so top 10% isn't so hard to reach.