User blog comment:LilyheartsLightning/A Year in Retrospectre/@comment-173.189.226.12-20130317193122/@comment-24174486-20130317200000

It is possible, albeit very difficult. You have to have destroyed the Collector Base, thus decreasing the EMS requirements for the Destroy variations. It requires you to have essentially done everything right (in the sense that you make the choices that get you the most EMS throughout the entire series), but it is possible.

And the volus in multiplayer makes perfect sense in-universe: it had already been established that the volus provided auxillary troops for the turians, and in the face of galactic war, most everyone who can fight will want to fight.