I believe that his home-life was probably dysfunctional, just looking at GA shows his understanding of what is and isn't normal in a family dynamic is skewed. In the book, Sally delights in trying to come up with punishments for Linda that will be as humiliating and upsetting as possible, and then it isn't Sally who learns a lesson, but Linda by deciding not to fight it anymore and just go with it. Check the end of chapter nine, Sally decides to force Linda to wear something to humiliate her in front of everyone (having already humiliated her multiple times through the book), and Linda just gives up and lets it happen. We have our hero Sally not learning to stop being an asshole, and Linda learning that being emotionally abused is just what she's gonna get in life so she may as well just accept it. This coming from the dude who rees nonstop about "mean-spiritedness" in cartoons. I can only come to the conclusion that he thinks a bit of emotional abuse in a family is normal and likely did experience that growing up.
A past of verbal abuse may also explain some of the things that set him off in cartoons. One of his most hated characters is the dad in Disney's Chicken Little movie. Buck, I think his name is. Buck is a bad father in the film, and a lot of his lines would be considered emotional abuse if someone overheard an actual father talking to their kid that way. Enter was
very angry in the Chicken Little review, mostly because of Buck. (Review linked below for some classic Enter rage.) And then when you think about other pieces of media he is familiar with and how certain characters don't enrage him as much as Buck, you start to notice he's more bothered by depictions of verbal abuse than of physical. Homer Simpson, for example, you would expect a person like him to rage about Homer strangling Bart, call it unfunny and consider Homer a terrible character as a result, but he's never shown up on any of his Most Hated Characters lists. It would make sense, though, if he experienced emotional abuse as a child, but nothing physical, then Buck would be the character to bring back those memories and not Homer.
Maybe even his freak-out over the MLP episode where one character insults the interests of some of the others (the one that Enter says sent him into a week long depression. The review is linked below, but I can't recall if he the depression comment was in the review or in his Top Worst MLP episodes video that came out later.), was because it somehow connected to memories of being verbally berated by his parents for the special-interests he had as a result of being an Autist. Just from the Pluto Is A Planet thing I posted earlier, I can imagine his parents yelling at him to stop playing vidya and watching cartoons and do his damn homework.
I dunno, this is all just speculation, but putting it together like this does cause some things to make sense.
https://youtube.com/watch?v=JhP0q9xW3qkhttps://youtube.com/watch?v=Bk2LCH-UqZ0