I don’t buy that he was as good as he claims. If he was, he would have continued playing brick and mortar games (which usually tend to be easier than online), and he would have at least one or two noteworthy tournament results, and he has none at all.
Live poker, especially tournament poker, is a completely game than online poker.
Online before the UIGEA Americans could legally play 24 tables at a time, which made playing poker like asset management or investing in the stock market; live poker is more akin to gambling - not that there isn’t (math) skill involved, but when your entire portfolio can ride on the result of a one hand at a time the results become as unstable as selling insurance to one client at a time.