The idea came from someone here in Michigan, but they’ve since had a falling out (even before the book). The idea has been developed into a series of bombardments by different kinds of crud, which arrive at different times because of their mass and velocity — but all of it coming from a sort of nearby star blowing up. The idea of mass extinction events coming from novae and supernovae isn’t new, there was a book by some other guy maybe ten years ago. I think I’ve got something about that on the drive...
The idea of an impact event at the beginning of the Holocene has been around for awhile. If they are finding Iridium at Clovis sites this may pinpoint the time and the reason for the Younger Dryas, which was world wide and should be able to be confirmed from sites out side of North America.
Firestone presumably had the goods to back it up, no?