You don't get your way by being passive. She's had to fight for what she has, and so Ouka's not afraid to be a little aggressive.

"Right, but... that wouldn't exactly help me fight against Team Rocket, would it?"

But he'll need to defeat the Gym Leader here, so it isn't like this is a decision that needs to be made right now. Not that Ouka hasn't already decided for him, regardless.