[Regardless of what his answer is, she already knows that whatever he tries won't work. If something as simple as their materia fails to work here, then of course something bigger won't. His words answer her question without directly saying so anyway.]

You stay out of our way and you'll have nothing to worry about, but this isn't about us.

[Not here, in this world.]

You start causing trouble with anyone, and I'll be the first to hear about it. We clear?