Yeah, don't sweat riding on the sidewalk when you have to. I too am a pretty assertive vehicular cyclist (well, my friends think I am insane as I force semi trucks to pass me on my road bike in summer) but I will say that icy roads are just too dangerous to let cars very close to you. Back roads are normally OK becuase cars will give you berth, but if the road is really icy just forget it and ride the sidwalk.

On icy roads, the bottom line is that you are going to go down sooner or later and the cars behind you won't be able to stop.