Violetta the cynical and self-doubting is unlikely to believe that she killed Madwa and/or that Madwa will stay dead if she did. (I'd love to know how Violetta fooled Steelgarter.) If she didn't puree Madwa's brain, Lucrezia can revive her. Even if she did, Lucrezia may have backups.

The win here is getting the lantern, without which even Madwa will have trouble taking out the whole crew, especially exhausted & when they have warning.