The fact she didnt kill Them, makes this series goes from pretty good to meh
The chapter already mentioned it: If Rose kill them (more specifically if they goes silent for too long) whatever 'failsafe' will be called into use.
i.e. the explosive rosary that the archbishop mention here (and UAV from agent side)
It's not like this is the first time the series have shown both side have backup plans:
The initial attempt to secure Rose/dad back with the restaurant was the protesters, the special squad was the backup.
Hibai called for the kidnapping as backup plan when Benika was still hesitant.
but I thought that she could make those sounds with her mouth? why would she need to set an alarm?
It's because they didn't see it that it made them flinch. Contrast this to the 'date' chapter where both of them were prepared to NOT react to the sound.
If Rose is only making the sound right in their face they wouldn't flinch since they'd know it's not real.
One option going forward is Gina switch side and after some negotiating with Babylon work under Hibai to guard dad/Benika.
Basically in return for providing protection for dad/Benika, Rose resume work with Babylon to deal with archbishop (since the stolen intel is gonna be recovered by Babylon at this rate)
Next step will be the archbishop pushing up schedule for his armed uprising plan I guess.