> more challenging problem to stop something coming back in from Space as opposed to an ICBM

Well, the reason I point out LEO is that Starfish Prime was detonated at 250 miles, that's within the range of a low Earth orbit. You don't need to return anything to Earth to have the desired effect, or even have it on an Earthward trajectory (such as deorbiting the satellite).

EDIT:

> would make this only likely form a truly rogue state

I do agree with this.