Whoever it is, that's something Chiaki might take personally. She thinks of the Lair Legion like an extended family. She understands her limits, so she wouldn't try a direct assault. But she's very likely to not only help them, but call in favors, blackmail, or intimidate if she needs to.

The other semi-related thought is that the vast majority of the criminal underworld doesn't want attention from the Lair Legion - so they would pretty much turn their backs on anyone who kills a Legionnaire.