Depressing comics week for Cyanide and Happiness? So business as usual? I haven't read any of these in years, decided to read some of the recent ones: http://explosm.net/comics/4125/ That one is gold.
you're overthinking it. the joke is that the man is sad because he loves his son, but his son's actions make it hard to love him. the punchline is revealed at the end when we find out that the son loves his father too, but can't show it because of whatever's wrong with him. that's the entirety of the joke.
course it is! it's in the same vein of humor as Nana's Everyday Life or as anything else that you laugh at to brush off sadness. it's all about laughing at fake people who're in real sad situations, so we don't need to laugh at real people in sad situations.