This is the survival half of the cosmic-ray safety argument: the exposure count is a measurement (see the flux observation), while this node records the uncontested background fact that the exposed bodies persist. The white-dwarf and neutron-star part carries the load for the hypothetical stable-neutral-black-hole case: their large observed populations at Gyr ages are what the Giddings-Mangano accretion argument turns on, since dense stars stop even neutral black holes and would be destroyed on short timescales, ending in highly visible explosive events that are not observed.