Can someone help me explain this yaoi manga Warui ko demo ii?

Why did Mikado act coldly to Towa after the incident at his house? I understand it was that "self study" but all he did was act cold to Towa??

"A sword is useless in the hands of a coward."

Hmm I think and this is purely my own opinion and translation of the situation - is that Mikado believe Towa was thinking so little of his feeling.
When Mikado's brother mention the word sex friend Towa started to freak out and then Mikado touch Towa asking what's wrong but Towa slap away his hand. Mikado realise that Towa has taken the teasing seriously and thinking maybe Mikado was using him for sex, despite Mikado affectionate approach towards Towa every chance he gets, hoping Towa would understand his feeling.
So he acted cold was probably his defense mechanism. Later while they were "doing it" 😉 Mikado ask if Towa hate the idea of being sex friends or just friends then how does he really feels? ~ This is just my own understanding anyone can refute it, I won't mind 🙂 ..

A good novel tells us the truth about its hero; but a bad novel tells us the truth about its author. - G.K Chesterton