Oliver didn't turn away but he also made no move towards Flint. If the Slytherin wnated to talk, well Oli wouldn't run but he wouldn't approach the other either. At least tonight he didn't want to get into some stupid fight with his favourite arch-rival.
It was celebration and not a pub, really. this was also a shcool, not that he'd cared about that when he was a student, but now he was kind of a professor, or teacher or something and getting into a scrap wouldn't be all too fortunate with the other adults around, especially not the Hogwarts staff.
so oliver settled for sipping on his drink slowly and just watching what everyone else was doing, for now.