Potasium iodide has never been in the picture at any of the outages I've been to... exposure levels aren't that high. I don't know enough about it's use to answer your question, but I'd bet that it's more of a (I'll be OK, I've got these pills) last ditch/last hope type of thing to build SOME level of false security... if I"m going to die from massive cancer, I'd just as soon get it over with right now... which brings us back to the train(chuckle, snicker).

And yes, decon is the first step... clean it up so you don't spread it around.

Troy