Insulting the CEO is rude, because insulting anyone is rude. There's nothing special about the CEO that makes it rude only to insult him.
The article even gives a better example here: casually introducing yourself to the CEO and making a joke. If the CEO feels insulted by this, it's because he has "Authority" and you are "not respecting it" - but wait, the other CEO I met really appreciated this! Suddenly it makes no sense. There's a special rule that this CEO insists I should know, but it's not even consistent with other CEOs. How am I supposed to know which authorities it's okay to make jokes with?
The article even gives a better example here: casually introducing yourself to the CEO and making a joke. If the CEO feels insulted by this, it's because he has "Authority" and you are "not respecting it" - but wait, the other CEO I met really appreciated this! Suddenly it makes no sense. There's a special rule that this CEO insists I should know, but it's not even consistent with other CEOs. How am I supposed to know which authorities it's okay to make jokes with?