Azazael was thrown out with us, but without reason. Balthazar, and Aziraphale too maybe, walked out of Heaven on their own.

For now. God would have to battle through the fallen to get to this place. [There was a relief, and a small amount of worry, in those thoughts. As the angels grew close to others that meant more targets, weaker targets, here if God or Michael made it to the Nexus.]