How could she forget something like that? Even though the capital and the Emperor all preached about peace and whatnot, they never really tried to put an end to the hunting of the non-humans either. Now that she thought about it, Siren hunting could be more or less considered legal even if the royal family never paid any attention to the Siren community, they have also turned a blind eye to the black market that sold Siren's blood and eyes.
If a noble had come here instead of the Duke, she really would have been killed right? Ginny knew that the nobles wouldn't have cared about stopping and thinking whether the woman in the lake was a human or Siren. They would have shot her dead the second their gazes fell on her, since they cared so little about her life they wouldn't have bothered with her at all.