A space-based nuke doesn't need to deorbit to be effective; starfish prime detonated at 400km, which is at the upper limit for a regular US keyhole satellite apogee and well in EMP range. Spy satellites also usually have really low perigrees and lots of delta-v to chase navies, so deorbiting isn't that big a deal for the things given a large enough lead time. In fact for the first part of their history spy satellites had to deorbit film in multiple return capsules, often even being caught in mid-air!

I will agree "Rods of God" type kinetic bombardment is stupid, though for different reasons