There is no good reason for murder, for future reference, but in this hypothetical case let's say to piss off the Malnosso because they can't function without test subjects. If everyone's dead, then they have nothing to work with until they bring all of us back. That'd be a stretch of their resources, time, and it'd be a stress so they'd be thinking less clearly and might make a mistake. Mistakes are always what give the most information, so it'd be a useful massacre.

[ Is it obvious she's thought about this? Maybe a little. ]