What horrible realization did Elie come to concerning Rabbi Eliahou?

The
horrible realization that Eliezer comes to is more of a statement of what is as opposed to what
should not be.  In the factory, after evacuating Buna, Eliezer and his father take turns
sleeping through the night.  While awake, Eliezer sees Rabbi Eliahou in search of his son. 
Eliezer realizes that the son abandoned the father while on the run in the belief that the
father would not make it and survive.  The estrangement of father...