I am myself an introvert so I get that very much. The pairing is about trying to diffuse the anxiety. If I feel it is not working well, there are ways to mitigate the issue. For many exercises, interaction can be a nightmare for introverts. I was organising a role play in a master course and I know I would have hated that when I was a student, but I am trying to rely on my own experience to avoid huge mistakes and making people too inconfortable. It is important to read the room but also to experiment to see what works and not!