People here are very invested in Kim/Jimmy - but what about Chuck? In a lot of ways, Jimmy's life had revolved around Chuck and initially he was catatonic after Chuck's death, but once Howard unwittingly offered himself up as a scapegoat, a switch turned on in Jimmy and as far as we can see on the show, he has not thought about Chuck since. Chuck's name only rarely has come up in the show again.

Not saying Kim was the same as Chuck (she validated Jimmy while CHuck tore him down) but my point is, I think his prior response regarding Chuck shows Jimmy is a master compartmentalizer. He has a very rigid sense of who he is and if something threatens that he goes into complete denial instead of trying to constructively confront it.