Didn't look like that to me. At that time, he wasn't that determined to be alone to grieve because he was on the phone. More like he reacted badly because he thought MC was trying to feel him up, when actually MC was just trying to keep him quiet. And before that, he cornered MC against the door and told him to fuck off *before* MC said "it's okay", reminding him of Tae Min. He knew the MC had just woken up from a *three month coma* and yet he was still going to deliver him into the other guys' hands to get beaten up, or beat him up himself.
No no no no no, too much drama ;___; I think it is just that he feels empty because he suddenly remembered about TaeMin.
Wait a sec in chp7 WooJin's friend said that recently WooJin has been "empty" was is because WOOJIN HEARD THAT TAE MIN "DIED"?!? That would explain why WooJin beat up the MC, because the thought that someone like the MC reminding him of Tae Min might be too much for a grieving WooJin. Also, WooJin saying "that's shitty" makes sense because to him its really shitty that Tae Min is dead.