Elias Vaughn wrote:
The Federation did consider genocide against the Borg, though. Picard only decided against when he actually spoke with Hugh.
Devil's advocate and all.
The strategy of attempted genocide against the Borg was initially proposed, but it was soon rejected upon more critical examination.
It was one of the brilliant insights of Destiny
to recognize that the drones didn't need killing, they needed liberating. The survival of the Federation and all of its neighbours was achieved through an act of mercy.
Section 31 would have been incapable of this breakthrough. Likely it would have attempted genocide against the Borg, failed due to its own limited knowledge, and set up the stage for comprehensive Borg retaliation against the Federation.