Either he is talking about what he did to her in the past.
Cause if he is mad about the fact he fought her like an actual warrior...then he is a punk bitch for aiming for the balls.
Nope, first MC mentioned that pink hair was holding his strength back and more "playing with soso".
Second (and more importantly): Soso herself mentions that pink hair was being a pervert, he was intentionally fighting closer to her than he need to, AND he was deliberately destroying her clothes during the match.
TL;DR: Pink hair is a pervert and deserved the swing to the nuts lol