Given the horrific things the Dominators have done and the suffering women like Midori have gone through, I can't blame them.
I mean, what did Mashiro expect was going to happen? Killing people in battle solves everything, but once you start subjugating territory and taking prisoners, what are you going to do with all the jailers, rapists, murderers, torturers, slavers and their accomplices? Take them to prisons they don't even have at this point?