It's an interesting thought. What fraction of cosmic ray muons per unit area must be scattered into Holmlid and Olafsson's detector to get the kinds of activity reported, given the amount of fuel they're working with? What energy will bring about the density (in the normal sense of the word) needed to have that kind of stopping power? Is this energy put into the system by the experimenter, or is it potential energy that was always there simply to be released, leading to the spontaneous formation of matter with an adequate density? If the energy was potential energy that was already there, what was the storage mechanism?
Cosmic muons penetrate far too much to make a difference is measurement on the ground level using a detector. They stop about 2 miles underground.