She's right but it moved too fast. It's a big leap from, "they got to die, no money for prison, and they deserve it" to "mutilation in the worst way possible".
I see this a lot in Isekai and Chinese novels that go for dark moments. In Isekai they are always like "This is that type of fantasy world" and just by saying that they are OK with death on mass. Then in Chinese novels they say "Strong control the weak" then do everything they can to be a strong person bullying the weak instead of changing the system.
I am sure she will be praised for this and get a bunch of followers. But if this is such a tough world, then executing prisoners is not hard nor is it very brave.
Better if she had to go through the difficulty of finding the criminals and proving their guilt, talking to the victims and this makes her take the extreme actions out sympathy and rage for the victims. Maybe show that other lords don't bother because finding the guilty is too hard or bothersome.