I'm not sure why his parents accept his lifestyle or let him get away with so much. They don't react to any of it. There's never even like, a jokey comment about him not paying rent or whatever. It's just literally off topic, always.
The only rational reason I can think of is because he is studying for his degree so they want him to finish that and will help him out until then other than that, I have no idea.
My parents would be on my case day and night if I wasn't working for more than a couple of weeks