There's also the little matter of how one defines a culture's "normal evolution" or "healthy development"; in addition to the aforementioned "letting them all die" aspect, if a society seems happy but social development has "stagnated", does that justify stepping in to nudge them in the right direction, or should you assume that they might possibly be able to do so in their own time?A common twist on the trope is to have such a law in effect, and then come across an alien race that is to gain tech and knowledge from the humans. Can you get away with telling the aliens You Are Not Ready?
Such interference includes the introduction of superior knowledge, strength, or technology to a world whose society is incapable of handling such advantages wisely."Even without ever having met a real culture from outer space, mankind has experienced firsthand the sort of disaster that can come from First Contact between a technologically-advanced society and a technologically-primitive and/or culturally-different one.
This also appears as the reason that aliens aware of our existence, or even visiting our planet in secret have not announced their presence to us.
Usually, the condition to join interstellar society is the independent development of starships or Faster-Than-Light Travel, or at least to starting to colonise other planets in the Solar System. Contrast Technology Uplift, when the aliens don't have this clause.
Where does the rule stop being about "preserving alien cultures" and start being about "keeping the humans (or The Federation) as the dominant power"?
One ironic inversion is to have a second, more advanced set of aliens show up and refuse to help because they have this exact same clause, essentially turning the tables and putting the protagonist on the receiving end of this "benign neglect".