The real world prior to act 6 was written to be based on video game logic. Sylladexes are literally a consumer product, characters are able to see the entire "sceen" they are in from the same angle as the viewer, and SBURB affecting the real world is only a slight surprise.
In this sort of world, Bro raising Dave to be a Puppeteer Ninja Master makes sense, and is not any more abusive than Dad throwing cakes at John to turn him into a Clown Master.
From act 6, the world is suddenly supposed to be "realistic". Beyond the literal game mechanic stuff like sylladexes being basically ignored, the whole alien conquest of earth is treated seriously and grimdarkly. Instead of a wacky situation, Roxy and Dirk are angsty warriors refugees from a war against the Empress. There are still jokes, but they are played to contrast the grim reality, while the jokes in the earlier story played along with the crazy game logic.
Now, when viewing the story from a realistic perspective, Bro is an abusive guardian, because anyone who does the things he did in real life would be sent to jail, and his children taken by CPS.
Hussie probably views it as a deconstruction, but it isn't. It's just a radical tone shift, and of course different actions seem different in different tones. It becomes doubly stupid when you realize that, by this logic, Dad, Mom, and Grandpa would also be considered abusive, perhaps even more than Bro, but Hussie decided to only focus on him for no real reason.
