Finally an MC with balls. BTW, he was no being rude here, Noona was also making shitty jokes to test if he was not a pushover. She already admitted to living with him for her own sake, and he agreed to her demands. So it's only fair that she listens to his demands (which was her aim to begin with).
It was kinda shitty the way it went, but our Noona here is a pedophile so MC has to act older than his age for a balanced relationship. I am more concerned why she's not in jail yet for sexually touching a minor.