@Misticsan Remember that outside plot armor Dominators are the ruling power with no contest. If both factions fight women will end losing or at best manage mutual destruction and that with a ton of plot armor.
The last thing you want is the give Dominators excuses to justify their actions or reasons to why Dominator forces cant surrender to women because they will suffer an horrible fate, so they will fight to the last
About what to do with the prisioners you have the option to put them to work (but not as expensable slaves) and earn their bed and food with their efforts. I bet that many dominators have very useful skills that women lack as mechanics, technicians etc that can be put to use.
What Mashiro is trying is basically tend bridges between the factions to see each other as equals, if the women faction act as bad as the dominators that means the dominator abuse is justified and normal, because is the fate of the strong to trample on the weak.
Remembers me on Warhammer 40k when Tau held off a punitive expedition force from the Imperium until was forced to retreat due to Tyranids atacking elsewhere and Tau thinking they were hot shit for defeating the Imperium army when it actually was a minuscule fraction that still managed to cripple the Tau planetary expansion.
And eye for an eye no longer is a viable option, moreso when one faction overpowers by far the other