I see it differently,
Arbee!
Maybe they are short of money. It is not easy to earn money as a tango teacher. These people were basically advertising for themselves at what was, for you, a social dance event. You wanted to enjoy the party, but the teachers mentioned had to work hard instead.
They already know the rules and don't need to be taught. The organizers should have communicated the nature of the event more clearly and enforce the rules if necessary. But they were probably too cowardly to do so. Not these teachers are the problem, the organizer was.