That was the plan, but we didn't account for just how large the Eggman Empire's army was. The leftover robots are everywhere. Even without Eggman to lead them, they're a constant threat, randomly attacking anyone they find.

We've got to stop the invasion before the city is overrun! 

But if you don't mind some direction, Knuckles went to investigate a town to the south. I haven't heard from him. So he might need your help.