I'm kind of at a loss as do how Section 31 won the war, it was the cure that they were unwilling to give that in the end won the war. And there was no accountability for Section 31's attempted use of genocide to end the war, If anything in creating Section 31 it gave the writers an out in allowing genocide to bve used and not have it blamed on the Federation.
Lets be fair, who started the war? Who was trying to enslave the other side? Who openly talked about destroying Earth? Don't play the game if you don't want to get hurt.
If they were to be held to account, they would be given medals and showered with praise.
Oto curing the female changeling was what helped win them the war. If there was no virus, that wouldn't have happened and a bloody last battle might have ensued costing millions of lives. Furthermore, it was the ultimate insurance policy in case things went downhill or remained a stalemate.