I've done that a few times over the years with my air hammer and this: Rotor/hub remover Mine is made by Mayhew, it gets the job done with my Thor Air Hammer and a little penetrating oil.Hit the edge of the rotor hat, pictured below, a few times, rotate the rotor 90 degrees, repeat. The rust should start to break away eventually.
Get a bigger hammer too, but don’t swing super hard, it’s all about creating a shock on the rotor/hub mating surface.View attachment 226293