Let's start with "what he showed." How can you know even know what that is without having trained with him?
How could you know anything about anybody you've never met?
For that matter, how do you know that the people who trained with him know what that is? Any number of them have said that various others of them didn't know - many of them said themselves that they didn't know.
Like anything else, you look at the information you have and form your opinion.
All of which is irrelevant to my point - which is just because somebody spent some time with someone doesn't mean that they are the best person to teach you what that person was doing.