I can imagine that, in this case for example, the inquiry might come to the conclusion that intervention was justified, but that efforts should have been taken to reduce the cultural contamination.
Perhaps the relocated species could have all been rendered unconscious for travel.
Failing that, they could have been relocated by a volunteer surgically altered to look like one of their own (assuming holo- technology of 2326 isn't up to the task of supplying an appropriate image) to avoid providing explicit imagery of helpful alien intercession. (This might seem pointless, but consider what would happen if this species were to now or at some point later be stumbled upon by a slaver species like the Hishmeri; with a bit of observation to hear about this myth they could fake being a return of Kitroth's people to more easily entice the relocated species into slavery.)
Failing that, just asking them to leave out details from the story that they pass on through the generations could achieve the same result (assuming they complied).
An inquiry into a prime directive violation doesn't have to be about whether or not intervention was appropriate. It could also be about the methods employed and the degree that the immediacy of the danger was balanced against minimizing cultural contamination.
Which is not to say that this intervention was mishandled, or that Captain th'Risrath necessarily did anything wrong. Maybe relocating this species in a way that didn't carry this story would have created a cultural crisis of its own and this was really the best way. Or maybe the threat was more immediate than this retelling makes it seem; and the attack on their last holdout was imminent. Or maybe they were getting close to the minimum genetic diversity threshold for long term survival and the Captain judged an open intervention as a more likely means to rescue a diverse enough population to be sustainable after being relocated. Or maybe some other factor(s) were at play.
I think an inquiry is relevant here (and in other cases where a non-intervention would result in genocide) to ask whether there was enough time to try to find a better way, and whether a better way existed to be found.
