they say only one man per generation is taught this.
Thats retarded. If it was so reliable and effective, then it would be taught widely. The old 'ooh, its too great a responsibility to give to many' argument doesn't hold any weight either, as if those not privy to the info want to kill someone, they can just get a gun and shoot their victim, or maybe take the more 'mundane' techniques like a foot stomp, and use it repeatedly on a skull till the victim expires. if the intent to kill is there, then knowing an alleged 'dim mak' will not really make the application of the intent any easier.
Open the knowledge up to indipendant scrutiny, and let the results speak for themeselves, dont obfuscate the truth with 'chosen one' BS.