The problem is that John's living and dying by what he thinks people are going to condemn him for doing is what, aside from an inability to admit that he's in the wrong, he has in common with Elly. An example of this is his need to clamp down what he assumes to be the rebelliousness of his children. What was going on, of course, was that he can't stand the fact that his children aren't cringingly grateful for the advantages he wishes he had at that age; since he's a pompous ninny who doesn't want to admit that his expectations of the world are revoltingly low, he can't help but convert a simple question into an act of vicious defiance because it keeps him from having to admit that what he assumes is generosity is actually a moral obligation as well as shielding himself from confronting the dangerous notion that what he calls decisiveness is actually poor impulse control. What we probably didn't see is that his relatives in Manitoba think of his endless complaints about how they have to instill good values in his ungrateful punk kids as the ravings of a hidebound ninny with a brain loaded with stereotypes he's too craven to question making yet another mountain out of a molehill; given how placid, tractable and stupid the alleged defiant criminal genius deviants always turn out to be, my guess is that Dan, Bev and Laura think that he's a prideful fool trying very hard to not admit that he married an imbecile and had subnormal children. They already know from his parents that he has an exaggerated concern for what people who turn out to not give a rodent's hindquarters might think of him and his and assume that he fears either public humiliation or (worse still) being pitied after being outed as the father of a clan of dolts.
Given that even his relatives assume that he's a pinheaded old dodo screaming about imaginary disasters, we can readily see why he seems to have adopted a sort of bunker mentality; that way, he can live out his paranoid fantasy about being singled out for public humiliation when confronted with things that scare him without facing the terrible prospect of hearing the horrible, horrible question "What exactly is the problem supposed to be again?" when he holds forth on how bad things are. He also gets to duck people who want to call him a pasty-faced, self-centered, child-hating, deceitful bully who'd rather scream and whine than be a man about things; since he'd rather die than admit that he isn't a straight shooter or a victim, avoiding Elly's wrath isn't the only thing that keeps him hidden away in his workshop. It's people who tell him to get over himself already that he fears more than rap music, gangs and outliving Elly and thus having to eat properly put together.