As in a number of other examples in the book and through that period of history (as well as today), Williams is trying to point out how willing the United States government was to gloss over possible dangers in order to maintain not just the public's trust but also the possibility of liability involved with the fallout from nuclear testing.  By trying to keep the stories under wraps as long as possible and then deftly heading them off with nice public service announcements once some of the problems became public, the American public was kept in the dark about the scope and nature of the dangers of nuclear testing.

There were a number of forces at work including paranoia about the Soviet threat that drove the military to test far more weapons than was ever necessary, the worry that any kind of backlash against nuclear weapons might hinder our efforts to keep the Soviets playing catch up, along with the general desire of the military to keep the public out of their affairs as they generally create a nuisance all helped to drive the kinds of public relations efforts that Williams was describing.