Three theories on that one:
1)She's a descendant from Pcell AND Dhomochevsky. Dhomochevsky is a safe guard so maybe she has a bit of safe guard in her that killy doesn't give a fuck anymore.
2) Killy has completed his own task and is independent of the system so he can do what ever the fuck he wants.
3) Pcell's daughter is hot enough to warrant saving.