This scene is self contained and explains itself. (It doesn't entirely line up with what we saw in Young Sheldon, but ignore that.)
After their father died, Sheldon went away to college and basically didn't support, help, or check in on his family. Their mother and the two older children had a difficult time and would have appreciated support, help, or just being asked after. But they pretended they were fine, and he didn't investigate that further or encourage them to be completely honest about how hard it was. Over time, Georgie developed anger about that, especially on behalf of his mother.
This is all brought up for the first time, apologized for, and resolved in this one scene. It's not really alluded to before or after except as a way of explaining why he's not particularly close with his siblings and doesn't visit them, have them to visit, talk about them, ask his friends to help him choose birthday and christmas presents for them etc etc.