""If you slowly get sick over three days you will recover ..." to die of cancer in a year or three. Chernobyl anyone?"
Remember that was a military booklet which means the emphasis is on your ability to fight after the event.
For troops in the field the standard for what is considered survival is different than for a civilian, many of us here remember what it was like to be a NATO troop in the Cold war, the purpose was to slow the assault while dying in place, hoping enough ships and aircraft would survive the crossing in time to save the remains of Western Europe.
Think of it as radiation therapy. You'll be immune to everything if you survive the treatment.