it’s an interesting touch that maul says the nightsisters were killed because they were “a threat to the EMPIRE,” considering that happened well before the empire came into being.

this is partially an appeal to ezra’s feelings (see the next line), but it’s also a nice reminder that maul knows more about the truth of how the empire came to be than just about anyone. it might be more accurate to say they were massacred because they were a threat to count dooku and darth sidious. but in the end, a threat to them and a threat to the empire is really the same thing, with different names.