I look at it differently. I just think he didn't want to be annoyed by a bunch of standard "sorry to hear about your loss" that many people receive when someone hears about their loss.
He said:
"I didn’t know how I was going to face all my friends at Los Alamos. I didn’t want people with long faces talking to me about the death of Arlene. "
To me "long faces" is the key. The long faces make him feel uncomfortable. Just like many people are comfortable singing in front of their parents and friends and showing emotions and others are not.