All of these professions would add to someones experience and aid them in teaching others how to protect themselves but that doesn't make that profession a complete education on the subject in and of itself. Its like asking a surfer to teach a scuba diving class. They operate in the same environments but with vastly different situations and goals.
People like this author pray on such assumptions to sell their snake oil. Its dishonest, irresponsible and can lead people into actions that can get them sued, arrested or killed.
Also does anyone else find it hilarios that the only art he claims rank in is drunken kung fu? How fitting for a bouncer.
Well remember the first rule of war: "know your enemy." :icon_chee
But how hard is it to kung fu a drunk, anyway? It's like Bill Cosby said: "red-eye makes you fight, and makes you LOSE.