I didn't really have the Prime Directive in mind when I mentioned non-interference, but rather whatever regulations Starfleet likely have in place that govern situations when they encounter a spacefaring race are not willing to enter into any sort of relationship.
It strikes me that if a Starfleet ship encounters such a race who politely tells them they're not interested in 'being friends' and to leave their space and not come calling again, then Starfleet would in all likelihood respect this and avoid that region in future.
So if these Sioux aliens fall into this category then Starfleet would likely respect their wishes and not infringe on their territory again, whereas your man on the street Federation citizen is not bound by the Starfleet MO and can do as they please.
Exactly, but the story in question involves those same men on the street running afoul of those self-same aliens and what would happen, and all I meant was the OP's analogy was incorrect, because of the Prime Directive, as other posters' suggestion that it take place in the TOS era is unnecessary, again, because of the Prime Directive.
The special regulations you're thinking about are really offshoots of the Prime Directive, if they exist at all, because having contact with a race that wants no contact can be considered "interference with their natural development."