just wondering why he follow his father rather than his mom
I'm guessing his mom just left on her own. If she left during the night and didn't bother taking her child... heck, they might not be divorced on paper, and they are "just living separately" and the dad is just too lazy to do anything about it.
The dad is correct that children are helpless without their parents, but he is being a hypocrite. He's not angry his son got suspended from school due to his actions, but still thinks he is being "good" by doing the bare minimum to keep his son alive. Parents choose to have kids (or take the risk of not using protection and having kids), so they are required to be responsible for them until they can fend for themselves. If you buy/adopt a pet, you have the responsibility to take care of them. Doing the bare minimum of what you are supposed to do won't get you an award. This dude is a toxic and really neglectful parent, and neglect is a form of abuse. It fucks you up in many ways, and it's hard to overcome, because "it's not like they hit you or anything". Well, in this case, the father is just an abusive pos.