i'd hope the guy she killed wasn't JUST a slave or something so that it's less...horrible
but she does seem like the kind of person to kill a bunch of innocent people for no TRULY justifiable reason.
Not justified, but understandable.
The two are not the same.
In a cruel world where people won't hesitate to backstab or kill to get what they want, morality is a risky thing to have.
Those slaves all had seen them, they even know what disguises they are using.
And not to mention that the ones they killed weren't exactly small no name people. Authorities are going to come in hard once news of his disappearance or deaths comes out.
We have seen previously how easy it is to bribe or intimidate people into giving info or doing their bidding.
Every slave there could easily spill the beans about who killed the guy and what/who they are disguised as.
Does it justify killing them out of paranoia? No, it doesn't.
It does, however, make her actions more understandable from a pragmatic standpoint.